Angles between vectors of center of two incirclesRelationship between circles touching incircleCan the angles be found?Angle Between Two TangentsHow to computer two Euler Angles between two vectorsUsing overlap area to determine distance between overlapping circlesSolve for quadrilateral with minimal difference between interior anglesFind the angles between two solidsWhy is the angle between vectors restricted?Shortest distance between two rectangles in 2D

Can others monetize my project with GPLv3?

How best to join tables, which have different lengths on the same column values which exist in both tables?

Build a mob of suspiciously happy lenny faces ( ͡° ͜ʖ ͡°)

How to detect a failed AES256 decryption programmatically?

Did Wernher von Braun really have a "Saturn V painted as the V2"?

Do banks' profitability really suffer under low interest rates

Does git delete empty folders?

Why should I pay for an SSL certificate?

Can sulfuric acid itself be electrolysed?

Why do aircraft leave the cruising altitude long before landing just to circle?

Just one file echoed from an array of files

Playing a fast but quiet Alberti bass

What causes burn marks on the air handler in the attic?

A curiosity on a first three natural numbers

Can the front glass be repaired of a broken lens?

Is it alright to say good afternoon Sirs and Madams in a panel interview?

Earliest evidence of objects intended for future archaeologists?

Why is su world executable?

Have made several mistakes during the course of my PhD. Can't help but feel resentment. Can I get some advice about how to move forward?

Independence of Mean and Variance of Discrete Uniform Distributions

Do living authors still get paid royalties for their old work?

Meaning of words заштырить and отштырить

Are there reliable, formulaic ways to form chords on the guitar?

Reducing contention in thread-safe LruCache



Angles between vectors of center of two incircles


Relationship between circles touching incircleCan the angles be found?Angle Between Two TangentsHow to computer two Euler Angles between two vectorsUsing overlap area to determine distance between overlapping circlesSolve for quadrilateral with minimal difference between interior anglesFind the angles between two solidsWhy is the angle between vectors restricted?Shortest distance between two rectangles in 2D






.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;








2












$begingroup$


I have two two incircle between rectangle and two
quadrilateral circlein. It's possible to determine exact value of $phi,$ angles between vectors of center of two circles.



enter image description here










share|cite|improve this question









$endgroup$




















    2












    $begingroup$


    I have two two incircle between rectangle and two
    quadrilateral circlein. It's possible to determine exact value of $phi,$ angles between vectors of center of two circles.



    enter image description here










    share|cite|improve this question









    $endgroup$
















      2












      2








      2


      3



      $begingroup$


      I have two two incircle between rectangle and two
      quadrilateral circlein. It's possible to determine exact value of $phi,$ angles between vectors of center of two circles.



      enter image description here










      share|cite|improve this question









      $endgroup$




      I have two two incircle between rectangle and two
      quadrilateral circlein. It's possible to determine exact value of $phi,$ angles between vectors of center of two circles.



      enter image description here







      geometry circles angle rectangles






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked 11 hours ago









      BarzanHayatiBarzanHayati

      4542 silver badges12 bronze badges




      4542 silver badges12 bronze badges























          4 Answers
          4






          active

          oldest

          votes


















          4












          $begingroup$

          Place the origin $O$ at the lower left-hand corner, and let the positive $x,y$-axes be the the natural choices based on the diagram.



          Let $r$ be the radius of the red circle.



          Let $P,Q$ be the centers of the circles of radii $2,1$, respectively.



          Then we can express the coordinates of $P,Q$ as $P=(x,2)$ and $Q=(x,r-1)$, where $x$ is an unknown.



          Computing $|OQ|$ in two ways, we get the equation
          $$sqrtx^2+(r-1)^2=r+1$$
          hence
          $$x^2+(r-1)^2=(r+1)^2tageq1$$
          Computing $|OP|$ in two ways, we get the equation
          $$sqrtx^2+2^2=r-2$$
          hence
          $$x^2+4=(r-2)^2tageq2$$
          From $(texteq1),-,(texteq2)$, we get $r=8$.



          Plugging $r=8$ into $(texteq2)$, we get $x=4sqrt2$.



          Using the known values of $r$ and $x$, the distance formula yields
          beginalign*
          |OP|&=6\[4pt]
          |OQ|&=9\[4pt]
          |PQ|&=5\[4pt]
          endalign*

          hence by the law of cosines, $cos(largephi)=largefrac2327$, so we get $largephi=cos^-1bigl(largefrac2327bigr)$.






          share|cite|improve this answer









          $endgroup$














          • $begingroup$
            that's slick!..
            $endgroup$
            – ganeshie8
            10 hours ago


















          2












          $begingroup$

          Using Pythagoras theorem is not difficult to find that the radius $B$ of red arcs is $8$. It follows that $PQ=6$, $PR=9$ and $QR=5$. Apply now the cosine rule to triangle $PQR$ to find
          $$
          cosphi=23over27.
          $$



          enter image description here






          share|cite|improve this answer









          $endgroup$






















            1












            $begingroup$

            enter image description here



            Let $|AB|=|CD|=a$,$|BC|=|AD|=b$,
            $|O_1E|=r_1$,
            $|O_2F|=r_2$,
            $angle O_1AO_2=phi$,
            $angle O_1AF=alpha$
            $angle O_2AF=beta$.



            Then
            beginalign
            tanalpha&=fracb-r_1a/2
            tag1label1
            ,\
            sinalpha&=fracb-r_1b+r_1
            ,\
            tanalpha&=fracsinalphasqrt1-sin^2alpha
            =fracb-r_1b+r_1
            left/
            sqrt1-Big( fracb-r_1b+r_1 Big)^2 right.
            =tfrac12,fracb-r_1sqrtb,r_1
            tag2label2
            .
            endalign



            From eqref1$=$eqref2 it follows
            beginalign
            a&=4,sqrtb,r_1
            tag3label3
            .
            endalign



            Similarly,
            beginalign
            tanbeta&=frac2r_2a
            tag4label4
            ,\
            sinbeta&=fracr_2b-r_2
            ,\
            tanbeta&=
            fracsinbetasqrt1-sin^2beta
            =fracr_2sqrtb,(b-2,r_2)
            tag5label5
            .
            endalign



            From eqref4$=$eqref5:
            beginalign
            a&=2,sqrtb,(b-2,r_2)
            tag6label6
            ,
            endalign



            and from eqref3$=$eqref6
            we have



            beginalign
            b&=4r_1+2r_2
            ,\
            a&=4,sqrtr_1,(4,r_1+2,r_2)
            .
            endalign



            beginalign
            tanphi&=tan(alpha-beta)
            =fractanalpha-tanbeta1+tanalphatanbeta
            =frac2(3r_1+r_2),sqrt2,r_1,(2,r_1+r_2)16,r_1^2+11,r_1,r_2+2,r_2^2
            endalign



            For $r_1=1$, $r_2=2$ we have



            beginalign
            a&=8,sqrt2approx 11.31370850
            ,\
            b&=8
            ,\
            phi&=arctanBig(frac10,sqrt223 Big)
            approx 31.586338^circ
            .
            endalign






            share|cite|improve this answer









            $endgroup$






















              0












              $begingroup$

              There are constraints that $A$ and $B$ must fullfil, i.e., the following system of equations coming from Pythagoras theorem applied to certain right triangles :



              $$begincases(B-2)^2+2^2=(A/2)^2\(B-1)^2+(A/2)^2=(B+1)^2endcases$$



              giving $A=8 sqrt2$ and $B=8$.



              If now we take equations as in the partial solution you gave (a good idea) :



              $$tan(theta) = dfrac2A/2 = dfracsqrt24tag1$$



              and



              $$tan(phi + theta) = dfrac74 sqrt2tag2$$



              Equation (2) can also be written :



              $$dfractan(phi) + tan(theta)1-tan(phi)tan(theta) = dfrac7sqrt28tag3$$



              from which we can extract the numerical value of $tan(phi)$. Up to you...






              share|cite|improve this answer











              $endgroup$














              • $begingroup$
                It would be great if you add your answer.
                $endgroup$
                – BarzanHayati
                10 hours ago










              • $begingroup$
                I am going to write it.
                $endgroup$
                – Jean Marie
                9 hours ago













              Your Answer








              StackExchange.ready(function()
              var channelOptions =
              tags: "".split(" "),
              id: "69"
              ;
              initTagRenderer("".split(" "), "".split(" "), channelOptions);

              StackExchange.using("externalEditor", function()
              // Have to fire editor after snippets, if snippets enabled
              if (StackExchange.settings.snippets.snippetsEnabled)
              StackExchange.using("snippets", function()
              createEditor();
              );

              else
              createEditor();

              );

              function createEditor()
              StackExchange.prepareEditor(
              heartbeatType: 'answer',
              autoActivateHeartbeat: false,
              convertImagesToLinks: true,
              noModals: true,
              showLowRepImageUploadWarning: true,
              reputationToPostImages: 10,
              bindNavPrevention: true,
              postfix: "",
              imageUploader:
              brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
              contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
              allowUrls: true
              ,
              noCode: true, onDemand: true,
              discardSelector: ".discard-answer"
              ,immediatelyShowMarkdownHelp:true
              );



              );













              draft saved

              draft discarded


















              StackExchange.ready(
              function ()
              StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3327157%2fangles-between-vectors-of-center-of-two-incircles%23new-answer', 'question_page');

              );

              Post as a guest















              Required, but never shown

























              4 Answers
              4






              active

              oldest

              votes








              4 Answers
              4






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes









              4












              $begingroup$

              Place the origin $O$ at the lower left-hand corner, and let the positive $x,y$-axes be the the natural choices based on the diagram.



              Let $r$ be the radius of the red circle.



              Let $P,Q$ be the centers of the circles of radii $2,1$, respectively.



              Then we can express the coordinates of $P,Q$ as $P=(x,2)$ and $Q=(x,r-1)$, where $x$ is an unknown.



              Computing $|OQ|$ in two ways, we get the equation
              $$sqrtx^2+(r-1)^2=r+1$$
              hence
              $$x^2+(r-1)^2=(r+1)^2tageq1$$
              Computing $|OP|$ in two ways, we get the equation
              $$sqrtx^2+2^2=r-2$$
              hence
              $$x^2+4=(r-2)^2tageq2$$
              From $(texteq1),-,(texteq2)$, we get $r=8$.



              Plugging $r=8$ into $(texteq2)$, we get $x=4sqrt2$.



              Using the known values of $r$ and $x$, the distance formula yields
              beginalign*
              |OP|&=6\[4pt]
              |OQ|&=9\[4pt]
              |PQ|&=5\[4pt]
              endalign*

              hence by the law of cosines, $cos(largephi)=largefrac2327$, so we get $largephi=cos^-1bigl(largefrac2327bigr)$.






              share|cite|improve this answer









              $endgroup$














              • $begingroup$
                that's slick!..
                $endgroup$
                – ganeshie8
                10 hours ago















              4












              $begingroup$

              Place the origin $O$ at the lower left-hand corner, and let the positive $x,y$-axes be the the natural choices based on the diagram.



              Let $r$ be the radius of the red circle.



              Let $P,Q$ be the centers of the circles of radii $2,1$, respectively.



              Then we can express the coordinates of $P,Q$ as $P=(x,2)$ and $Q=(x,r-1)$, where $x$ is an unknown.



              Computing $|OQ|$ in two ways, we get the equation
              $$sqrtx^2+(r-1)^2=r+1$$
              hence
              $$x^2+(r-1)^2=(r+1)^2tageq1$$
              Computing $|OP|$ in two ways, we get the equation
              $$sqrtx^2+2^2=r-2$$
              hence
              $$x^2+4=(r-2)^2tageq2$$
              From $(texteq1),-,(texteq2)$, we get $r=8$.



              Plugging $r=8$ into $(texteq2)$, we get $x=4sqrt2$.



              Using the known values of $r$ and $x$, the distance formula yields
              beginalign*
              |OP|&=6\[4pt]
              |OQ|&=9\[4pt]
              |PQ|&=5\[4pt]
              endalign*

              hence by the law of cosines, $cos(largephi)=largefrac2327$, so we get $largephi=cos^-1bigl(largefrac2327bigr)$.






              share|cite|improve this answer









              $endgroup$














              • $begingroup$
                that's slick!..
                $endgroup$
                – ganeshie8
                10 hours ago













              4












              4








              4





              $begingroup$

              Place the origin $O$ at the lower left-hand corner, and let the positive $x,y$-axes be the the natural choices based on the diagram.



              Let $r$ be the radius of the red circle.



              Let $P,Q$ be the centers of the circles of radii $2,1$, respectively.



              Then we can express the coordinates of $P,Q$ as $P=(x,2)$ and $Q=(x,r-1)$, where $x$ is an unknown.



              Computing $|OQ|$ in two ways, we get the equation
              $$sqrtx^2+(r-1)^2=r+1$$
              hence
              $$x^2+(r-1)^2=(r+1)^2tageq1$$
              Computing $|OP|$ in two ways, we get the equation
              $$sqrtx^2+2^2=r-2$$
              hence
              $$x^2+4=(r-2)^2tageq2$$
              From $(texteq1),-,(texteq2)$, we get $r=8$.



              Plugging $r=8$ into $(texteq2)$, we get $x=4sqrt2$.



              Using the known values of $r$ and $x$, the distance formula yields
              beginalign*
              |OP|&=6\[4pt]
              |OQ|&=9\[4pt]
              |PQ|&=5\[4pt]
              endalign*

              hence by the law of cosines, $cos(largephi)=largefrac2327$, so we get $largephi=cos^-1bigl(largefrac2327bigr)$.






              share|cite|improve this answer









              $endgroup$



              Place the origin $O$ at the lower left-hand corner, and let the positive $x,y$-axes be the the natural choices based on the diagram.



              Let $r$ be the radius of the red circle.



              Let $P,Q$ be the centers of the circles of radii $2,1$, respectively.



              Then we can express the coordinates of $P,Q$ as $P=(x,2)$ and $Q=(x,r-1)$, where $x$ is an unknown.



              Computing $|OQ|$ in two ways, we get the equation
              $$sqrtx^2+(r-1)^2=r+1$$
              hence
              $$x^2+(r-1)^2=(r+1)^2tageq1$$
              Computing $|OP|$ in two ways, we get the equation
              $$sqrtx^2+2^2=r-2$$
              hence
              $$x^2+4=(r-2)^2tageq2$$
              From $(texteq1),-,(texteq2)$, we get $r=8$.



              Plugging $r=8$ into $(texteq2)$, we get $x=4sqrt2$.



              Using the known values of $r$ and $x$, the distance formula yields
              beginalign*
              |OP|&=6\[4pt]
              |OQ|&=9\[4pt]
              |PQ|&=5\[4pt]
              endalign*

              hence by the law of cosines, $cos(largephi)=largefrac2327$, so we get $largephi=cos^-1bigl(largefrac2327bigr)$.







              share|cite|improve this answer












              share|cite|improve this answer



              share|cite|improve this answer










              answered 10 hours ago









              quasiquasi

              40.3k3 gold badges29 silver badges71 bronze badges




              40.3k3 gold badges29 silver badges71 bronze badges














              • $begingroup$
                that's slick!..
                $endgroup$
                – ganeshie8
                10 hours ago
















              • $begingroup$
                that's slick!..
                $endgroup$
                – ganeshie8
                10 hours ago















              $begingroup$
              that's slick!..
              $endgroup$
              – ganeshie8
              10 hours ago




              $begingroup$
              that's slick!..
              $endgroup$
              – ganeshie8
              10 hours ago













              2












              $begingroup$

              Using Pythagoras theorem is not difficult to find that the radius $B$ of red arcs is $8$. It follows that $PQ=6$, $PR=9$ and $QR=5$. Apply now the cosine rule to triangle $PQR$ to find
              $$
              cosphi=23over27.
              $$



              enter image description here






              share|cite|improve this answer









              $endgroup$



















                2












                $begingroup$

                Using Pythagoras theorem is not difficult to find that the radius $B$ of red arcs is $8$. It follows that $PQ=6$, $PR=9$ and $QR=5$. Apply now the cosine rule to triangle $PQR$ to find
                $$
                cosphi=23over27.
                $$



                enter image description here






                share|cite|improve this answer









                $endgroup$

















                  2












                  2








                  2





                  $begingroup$

                  Using Pythagoras theorem is not difficult to find that the radius $B$ of red arcs is $8$. It follows that $PQ=6$, $PR=9$ and $QR=5$. Apply now the cosine rule to triangle $PQR$ to find
                  $$
                  cosphi=23over27.
                  $$



                  enter image description here






                  share|cite|improve this answer









                  $endgroup$



                  Using Pythagoras theorem is not difficult to find that the radius $B$ of red arcs is $8$. It follows that $PQ=6$, $PR=9$ and $QR=5$. Apply now the cosine rule to triangle $PQR$ to find
                  $$
                  cosphi=23over27.
                  $$



                  enter image description here







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered 10 hours ago









                  AretinoAretino

                  27.4k3 gold badges20 silver badges48 bronze badges




                  27.4k3 gold badges20 silver badges48 bronze badges
























                      1












                      $begingroup$

                      enter image description here



                      Let $|AB|=|CD|=a$,$|BC|=|AD|=b$,
                      $|O_1E|=r_1$,
                      $|O_2F|=r_2$,
                      $angle O_1AO_2=phi$,
                      $angle O_1AF=alpha$
                      $angle O_2AF=beta$.



                      Then
                      beginalign
                      tanalpha&=fracb-r_1a/2
                      tag1label1
                      ,\
                      sinalpha&=fracb-r_1b+r_1
                      ,\
                      tanalpha&=fracsinalphasqrt1-sin^2alpha
                      =fracb-r_1b+r_1
                      left/
                      sqrt1-Big( fracb-r_1b+r_1 Big)^2 right.
                      =tfrac12,fracb-r_1sqrtb,r_1
                      tag2label2
                      .
                      endalign



                      From eqref1$=$eqref2 it follows
                      beginalign
                      a&=4,sqrtb,r_1
                      tag3label3
                      .
                      endalign



                      Similarly,
                      beginalign
                      tanbeta&=frac2r_2a
                      tag4label4
                      ,\
                      sinbeta&=fracr_2b-r_2
                      ,\
                      tanbeta&=
                      fracsinbetasqrt1-sin^2beta
                      =fracr_2sqrtb,(b-2,r_2)
                      tag5label5
                      .
                      endalign



                      From eqref4$=$eqref5:
                      beginalign
                      a&=2,sqrtb,(b-2,r_2)
                      tag6label6
                      ,
                      endalign



                      and from eqref3$=$eqref6
                      we have



                      beginalign
                      b&=4r_1+2r_2
                      ,\
                      a&=4,sqrtr_1,(4,r_1+2,r_2)
                      .
                      endalign



                      beginalign
                      tanphi&=tan(alpha-beta)
                      =fractanalpha-tanbeta1+tanalphatanbeta
                      =frac2(3r_1+r_2),sqrt2,r_1,(2,r_1+r_2)16,r_1^2+11,r_1,r_2+2,r_2^2
                      endalign



                      For $r_1=1$, $r_2=2$ we have



                      beginalign
                      a&=8,sqrt2approx 11.31370850
                      ,\
                      b&=8
                      ,\
                      phi&=arctanBig(frac10,sqrt223 Big)
                      approx 31.586338^circ
                      .
                      endalign






                      share|cite|improve this answer









                      $endgroup$



















                        1












                        $begingroup$

                        enter image description here



                        Let $|AB|=|CD|=a$,$|BC|=|AD|=b$,
                        $|O_1E|=r_1$,
                        $|O_2F|=r_2$,
                        $angle O_1AO_2=phi$,
                        $angle O_1AF=alpha$
                        $angle O_2AF=beta$.



                        Then
                        beginalign
                        tanalpha&=fracb-r_1a/2
                        tag1label1
                        ,\
                        sinalpha&=fracb-r_1b+r_1
                        ,\
                        tanalpha&=fracsinalphasqrt1-sin^2alpha
                        =fracb-r_1b+r_1
                        left/
                        sqrt1-Big( fracb-r_1b+r_1 Big)^2 right.
                        =tfrac12,fracb-r_1sqrtb,r_1
                        tag2label2
                        .
                        endalign



                        From eqref1$=$eqref2 it follows
                        beginalign
                        a&=4,sqrtb,r_1
                        tag3label3
                        .
                        endalign



                        Similarly,
                        beginalign
                        tanbeta&=frac2r_2a
                        tag4label4
                        ,\
                        sinbeta&=fracr_2b-r_2
                        ,\
                        tanbeta&=
                        fracsinbetasqrt1-sin^2beta
                        =fracr_2sqrtb,(b-2,r_2)
                        tag5label5
                        .
                        endalign



                        From eqref4$=$eqref5:
                        beginalign
                        a&=2,sqrtb,(b-2,r_2)
                        tag6label6
                        ,
                        endalign



                        and from eqref3$=$eqref6
                        we have



                        beginalign
                        b&=4r_1+2r_2
                        ,\
                        a&=4,sqrtr_1,(4,r_1+2,r_2)
                        .
                        endalign



                        beginalign
                        tanphi&=tan(alpha-beta)
                        =fractanalpha-tanbeta1+tanalphatanbeta
                        =frac2(3r_1+r_2),sqrt2,r_1,(2,r_1+r_2)16,r_1^2+11,r_1,r_2+2,r_2^2
                        endalign



                        For $r_1=1$, $r_2=2$ we have



                        beginalign
                        a&=8,sqrt2approx 11.31370850
                        ,\
                        b&=8
                        ,\
                        phi&=arctanBig(frac10,sqrt223 Big)
                        approx 31.586338^circ
                        .
                        endalign






                        share|cite|improve this answer









                        $endgroup$

















                          1












                          1








                          1





                          $begingroup$

                          enter image description here



                          Let $|AB|=|CD|=a$,$|BC|=|AD|=b$,
                          $|O_1E|=r_1$,
                          $|O_2F|=r_2$,
                          $angle O_1AO_2=phi$,
                          $angle O_1AF=alpha$
                          $angle O_2AF=beta$.



                          Then
                          beginalign
                          tanalpha&=fracb-r_1a/2
                          tag1label1
                          ,\
                          sinalpha&=fracb-r_1b+r_1
                          ,\
                          tanalpha&=fracsinalphasqrt1-sin^2alpha
                          =fracb-r_1b+r_1
                          left/
                          sqrt1-Big( fracb-r_1b+r_1 Big)^2 right.
                          =tfrac12,fracb-r_1sqrtb,r_1
                          tag2label2
                          .
                          endalign



                          From eqref1$=$eqref2 it follows
                          beginalign
                          a&=4,sqrtb,r_1
                          tag3label3
                          .
                          endalign



                          Similarly,
                          beginalign
                          tanbeta&=frac2r_2a
                          tag4label4
                          ,\
                          sinbeta&=fracr_2b-r_2
                          ,\
                          tanbeta&=
                          fracsinbetasqrt1-sin^2beta
                          =fracr_2sqrtb,(b-2,r_2)
                          tag5label5
                          .
                          endalign



                          From eqref4$=$eqref5:
                          beginalign
                          a&=2,sqrtb,(b-2,r_2)
                          tag6label6
                          ,
                          endalign



                          and from eqref3$=$eqref6
                          we have



                          beginalign
                          b&=4r_1+2r_2
                          ,\
                          a&=4,sqrtr_1,(4,r_1+2,r_2)
                          .
                          endalign



                          beginalign
                          tanphi&=tan(alpha-beta)
                          =fractanalpha-tanbeta1+tanalphatanbeta
                          =frac2(3r_1+r_2),sqrt2,r_1,(2,r_1+r_2)16,r_1^2+11,r_1,r_2+2,r_2^2
                          endalign



                          For $r_1=1$, $r_2=2$ we have



                          beginalign
                          a&=8,sqrt2approx 11.31370850
                          ,\
                          b&=8
                          ,\
                          phi&=arctanBig(frac10,sqrt223 Big)
                          approx 31.586338^circ
                          .
                          endalign






                          share|cite|improve this answer









                          $endgroup$



                          enter image description here



                          Let $|AB|=|CD|=a$,$|BC|=|AD|=b$,
                          $|O_1E|=r_1$,
                          $|O_2F|=r_2$,
                          $angle O_1AO_2=phi$,
                          $angle O_1AF=alpha$
                          $angle O_2AF=beta$.



                          Then
                          beginalign
                          tanalpha&=fracb-r_1a/2
                          tag1label1
                          ,\
                          sinalpha&=fracb-r_1b+r_1
                          ,\
                          tanalpha&=fracsinalphasqrt1-sin^2alpha
                          =fracb-r_1b+r_1
                          left/
                          sqrt1-Big( fracb-r_1b+r_1 Big)^2 right.
                          =tfrac12,fracb-r_1sqrtb,r_1
                          tag2label2
                          .
                          endalign



                          From eqref1$=$eqref2 it follows
                          beginalign
                          a&=4,sqrtb,r_1
                          tag3label3
                          .
                          endalign



                          Similarly,
                          beginalign
                          tanbeta&=frac2r_2a
                          tag4label4
                          ,\
                          sinbeta&=fracr_2b-r_2
                          ,\
                          tanbeta&=
                          fracsinbetasqrt1-sin^2beta
                          =fracr_2sqrtb,(b-2,r_2)
                          tag5label5
                          .
                          endalign



                          From eqref4$=$eqref5:
                          beginalign
                          a&=2,sqrtb,(b-2,r_2)
                          tag6label6
                          ,
                          endalign



                          and from eqref3$=$eqref6
                          we have



                          beginalign
                          b&=4r_1+2r_2
                          ,\
                          a&=4,sqrtr_1,(4,r_1+2,r_2)
                          .
                          endalign



                          beginalign
                          tanphi&=tan(alpha-beta)
                          =fractanalpha-tanbeta1+tanalphatanbeta
                          =frac2(3r_1+r_2),sqrt2,r_1,(2,r_1+r_2)16,r_1^2+11,r_1,r_2+2,r_2^2
                          endalign



                          For $r_1=1$, $r_2=2$ we have



                          beginalign
                          a&=8,sqrt2approx 11.31370850
                          ,\
                          b&=8
                          ,\
                          phi&=arctanBig(frac10,sqrt223 Big)
                          approx 31.586338^circ
                          .
                          endalign







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered 53 mins ago









                          g.kovg.kov

                          6,8111 gold badge8 silver badges23 bronze badges




                          6,8111 gold badge8 silver badges23 bronze badges
























                              0












                              $begingroup$

                              There are constraints that $A$ and $B$ must fullfil, i.e., the following system of equations coming from Pythagoras theorem applied to certain right triangles :



                              $$begincases(B-2)^2+2^2=(A/2)^2\(B-1)^2+(A/2)^2=(B+1)^2endcases$$



                              giving $A=8 sqrt2$ and $B=8$.



                              If now we take equations as in the partial solution you gave (a good idea) :



                              $$tan(theta) = dfrac2A/2 = dfracsqrt24tag1$$



                              and



                              $$tan(phi + theta) = dfrac74 sqrt2tag2$$



                              Equation (2) can also be written :



                              $$dfractan(phi) + tan(theta)1-tan(phi)tan(theta) = dfrac7sqrt28tag3$$



                              from which we can extract the numerical value of $tan(phi)$. Up to you...






                              share|cite|improve this answer











                              $endgroup$














                              • $begingroup$
                                It would be great if you add your answer.
                                $endgroup$
                                – BarzanHayati
                                10 hours ago










                              • $begingroup$
                                I am going to write it.
                                $endgroup$
                                – Jean Marie
                                9 hours ago















                              0












                              $begingroup$

                              There are constraints that $A$ and $B$ must fullfil, i.e., the following system of equations coming from Pythagoras theorem applied to certain right triangles :



                              $$begincases(B-2)^2+2^2=(A/2)^2\(B-1)^2+(A/2)^2=(B+1)^2endcases$$



                              giving $A=8 sqrt2$ and $B=8$.



                              If now we take equations as in the partial solution you gave (a good idea) :



                              $$tan(theta) = dfrac2A/2 = dfracsqrt24tag1$$



                              and



                              $$tan(phi + theta) = dfrac74 sqrt2tag2$$



                              Equation (2) can also be written :



                              $$dfractan(phi) + tan(theta)1-tan(phi)tan(theta) = dfrac7sqrt28tag3$$



                              from which we can extract the numerical value of $tan(phi)$. Up to you...






                              share|cite|improve this answer











                              $endgroup$














                              • $begingroup$
                                It would be great if you add your answer.
                                $endgroup$
                                – BarzanHayati
                                10 hours ago










                              • $begingroup$
                                I am going to write it.
                                $endgroup$
                                – Jean Marie
                                9 hours ago













                              0












                              0








                              0





                              $begingroup$

                              There are constraints that $A$ and $B$ must fullfil, i.e., the following system of equations coming from Pythagoras theorem applied to certain right triangles :



                              $$begincases(B-2)^2+2^2=(A/2)^2\(B-1)^2+(A/2)^2=(B+1)^2endcases$$



                              giving $A=8 sqrt2$ and $B=8$.



                              If now we take equations as in the partial solution you gave (a good idea) :



                              $$tan(theta) = dfrac2A/2 = dfracsqrt24tag1$$



                              and



                              $$tan(phi + theta) = dfrac74 sqrt2tag2$$



                              Equation (2) can also be written :



                              $$dfractan(phi) + tan(theta)1-tan(phi)tan(theta) = dfrac7sqrt28tag3$$



                              from which we can extract the numerical value of $tan(phi)$. Up to you...






                              share|cite|improve this answer











                              $endgroup$



                              There are constraints that $A$ and $B$ must fullfil, i.e., the following system of equations coming from Pythagoras theorem applied to certain right triangles :



                              $$begincases(B-2)^2+2^2=(A/2)^2\(B-1)^2+(A/2)^2=(B+1)^2endcases$$



                              giving $A=8 sqrt2$ and $B=8$.



                              If now we take equations as in the partial solution you gave (a good idea) :



                              $$tan(theta) = dfrac2A/2 = dfracsqrt24tag1$$



                              and



                              $$tan(phi + theta) = dfrac74 sqrt2tag2$$



                              Equation (2) can also be written :



                              $$dfractan(phi) + tan(theta)1-tan(phi)tan(theta) = dfrac7sqrt28tag3$$



                              from which we can extract the numerical value of $tan(phi)$. Up to you...







                              share|cite|improve this answer














                              share|cite|improve this answer



                              share|cite|improve this answer








                              edited 8 hours ago

























                              answered 10 hours ago









                              Jean MarieJean Marie

                              34.5k4 gold badges26 silver badges60 bronze badges




                              34.5k4 gold badges26 silver badges60 bronze badges














                              • $begingroup$
                                It would be great if you add your answer.
                                $endgroup$
                                – BarzanHayati
                                10 hours ago










                              • $begingroup$
                                I am going to write it.
                                $endgroup$
                                – Jean Marie
                                9 hours ago
















                              • $begingroup$
                                It would be great if you add your answer.
                                $endgroup$
                                – BarzanHayati
                                10 hours ago










                              • $begingroup$
                                I am going to write it.
                                $endgroup$
                                – Jean Marie
                                9 hours ago















                              $begingroup$
                              It would be great if you add your answer.
                              $endgroup$
                              – BarzanHayati
                              10 hours ago




                              $begingroup$
                              It would be great if you add your answer.
                              $endgroup$
                              – BarzanHayati
                              10 hours ago












                              $begingroup$
                              I am going to write it.
                              $endgroup$
                              – Jean Marie
                              9 hours ago




                              $begingroup$
                              I am going to write it.
                              $endgroup$
                              – Jean Marie
                              9 hours ago

















                              draft saved

                              draft discarded
















































                              Thanks for contributing an answer to Mathematics Stack Exchange!


                              • Please be sure to answer the question. Provide details and share your research!

                              But avoid


                              • Asking for help, clarification, or responding to other answers.

                              • Making statements based on opinion; back them up with references or personal experience.

                              Use MathJax to format equations. MathJax reference.


                              To learn more, see our tips on writing great answers.




                              draft saved


                              draft discarded














                              StackExchange.ready(
                              function ()
                              StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3327157%2fangles-between-vectors-of-center-of-two-incircles%23new-answer', 'question_page');

                              );

                              Post as a guest















                              Required, but never shown





















































                              Required, but never shown














                              Required, but never shown












                              Required, but never shown







                              Required, but never shown

































                              Required, but never shown














                              Required, but never shown












                              Required, but never shown







                              Required, but never shown







                              Popular posts from this blog

                              Canceling a color specificationRandomly assigning color to Graphics3D objects?Default color for Filling in Mathematica 9Coloring specific elements of sets with a prime modified order in an array plotHow to pick a color differing significantly from the colors already in a given color list?Detection of the text colorColor numbers based on their valueCan color schemes for use with ColorData include opacity specification?My dynamic color schemes

                              Invision Community Contents History See also References External links Navigation menuProprietaryinvisioncommunity.comIPS Community ForumsIPS Community Forumsthis blog entry"License Changes, IP.Board 3.4, and the Future""Interview -- Matt Mecham of Ibforums""CEO Invision Power Board, Matt Mecham Is a Liar, Thief!"IPB License Explanation 1.3, 1.3.1, 2.0, and 2.1ArchivedSecurity Fixes, Updates And Enhancements For IPB 1.3.1Archived"New Demo Accounts - Invision Power Services"the original"New Default Skin"the original"Invision Power Board 3.0.0 and Applications Released"the original"Archived copy"the original"Perpetual licenses being done away with""Release Notes - Invision Power Services""Introducing: IPS Community Suite 4!"Invision Community Release Notes

                              199年 目錄 大件事 到箇年出世嗰人 到箇年死嗰人 節慶、風俗習慣 導覽選單