A trigonometry problem for a graphic designer (includes graphic)












1












$begingroup$


I am in no way a mathematician, I am a graphic designer by trade but I do like precision in what I do.



Quite a tricky one to describe hence the attached graphic, however, in words;




I have punched a circle out of a square of the same dimensions. I have discarded all but the top left corner shape. I'd now like to round this corner off. So at 30 degrees from the top right I have created a point, from this point I'd like to draw a circle (green) until it fills the available space.



I therefore want to calculate the radius of the green circle. But my limited maths knowledge means I'm struggling and would be very grateful for any help.



I have the angles a, b and c. I also have the lengths of d, e and f.




rounded-corner










share|cite|improve this question











$endgroup$

















    1












    $begingroup$


    I am in no way a mathematician, I am a graphic designer by trade but I do like precision in what I do.



    Quite a tricky one to describe hence the attached graphic, however, in words;




    I have punched a circle out of a square of the same dimensions. I have discarded all but the top left corner shape. I'd now like to round this corner off. So at 30 degrees from the top right I have created a point, from this point I'd like to draw a circle (green) until it fills the available space.



    I therefore want to calculate the radius of the green circle. But my limited maths knowledge means I'm struggling and would be very grateful for any help.



    I have the angles a, b and c. I also have the lengths of d, e and f.




    rounded-corner










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      I am in no way a mathematician, I am a graphic designer by trade but I do like precision in what I do.



      Quite a tricky one to describe hence the attached graphic, however, in words;




      I have punched a circle out of a square of the same dimensions. I have discarded all but the top left corner shape. I'd now like to round this corner off. So at 30 degrees from the top right I have created a point, from this point I'd like to draw a circle (green) until it fills the available space.



      I therefore want to calculate the radius of the green circle. But my limited maths knowledge means I'm struggling and would be very grateful for any help.



      I have the angles a, b and c. I also have the lengths of d, e and f.




      rounded-corner










      share|cite|improve this question











      $endgroup$




      I am in no way a mathematician, I am a graphic designer by trade but I do like precision in what I do.



      Quite a tricky one to describe hence the attached graphic, however, in words;




      I have punched a circle out of a square of the same dimensions. I have discarded all but the top left corner shape. I'd now like to round this corner off. So at 30 degrees from the top right I have created a point, from this point I'd like to draw a circle (green) until it fills the available space.



      I therefore want to calculate the radius of the green circle. But my limited maths knowledge means I'm struggling and would be very grateful for any help.



      I have the angles a, b and c. I also have the lengths of d, e and f.




      rounded-corner







      trigonometry






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Jan 31 at 17:59









      Blue

      49.5k870157




      49.5k870157










      asked Jan 31 at 17:03









      morgyfacemorgyface

      82




      82






















          1 Answer
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          0












          $begingroup$

          If radius of green circle is $r$, then for length $OD$:
          $$
          OD = OB+BC+CD,\
          frac d{cos a} = d + r + frac r{cos a},\
          rleft(frac 1{cos a}+1right) = dleft(frac 1{cos a}-1right)
          r = dfrac{1-cos a}{1+cos a}
          $$



          If $a=30°$, then $r = (7-4sqrt 3)d approx 0.0718 d$.



          enter image description here






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            This is mind blowing, I quickly finished off the design work after sizing the green circle correctly, and I'm now returning to try and get my head round the equation. I'm incredibly grateful for the help, thank you @vasily-mitch
            $endgroup$
            – morgyface
            Jan 31 at 18:49










          • $begingroup$
            Glad to help. You might refresh basic trigonometry in a right triangle and notice the similarity between small red triangle and big $OAD$
            $endgroup$
            – Vasily Mitch
            Jan 31 at 18:57












          Your Answer





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          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

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          0












          $begingroup$

          If radius of green circle is $r$, then for length $OD$:
          $$
          OD = OB+BC+CD,\
          frac d{cos a} = d + r + frac r{cos a},\
          rleft(frac 1{cos a}+1right) = dleft(frac 1{cos a}-1right)
          r = dfrac{1-cos a}{1+cos a}
          $$



          If $a=30°$, then $r = (7-4sqrt 3)d approx 0.0718 d$.



          enter image description here






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            This is mind blowing, I quickly finished off the design work after sizing the green circle correctly, and I'm now returning to try and get my head round the equation. I'm incredibly grateful for the help, thank you @vasily-mitch
            $endgroup$
            – morgyface
            Jan 31 at 18:49










          • $begingroup$
            Glad to help. You might refresh basic trigonometry in a right triangle and notice the similarity between small red triangle and big $OAD$
            $endgroup$
            – Vasily Mitch
            Jan 31 at 18:57
















          0












          $begingroup$

          If radius of green circle is $r$, then for length $OD$:
          $$
          OD = OB+BC+CD,\
          frac d{cos a} = d + r + frac r{cos a},\
          rleft(frac 1{cos a}+1right) = dleft(frac 1{cos a}-1right)
          r = dfrac{1-cos a}{1+cos a}
          $$



          If $a=30°$, then $r = (7-4sqrt 3)d approx 0.0718 d$.



          enter image description here






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            This is mind blowing, I quickly finished off the design work after sizing the green circle correctly, and I'm now returning to try and get my head round the equation. I'm incredibly grateful for the help, thank you @vasily-mitch
            $endgroup$
            – morgyface
            Jan 31 at 18:49










          • $begingroup$
            Glad to help. You might refresh basic trigonometry in a right triangle and notice the similarity between small red triangle and big $OAD$
            $endgroup$
            – Vasily Mitch
            Jan 31 at 18:57














          0












          0








          0





          $begingroup$

          If radius of green circle is $r$, then for length $OD$:
          $$
          OD = OB+BC+CD,\
          frac d{cos a} = d + r + frac r{cos a},\
          rleft(frac 1{cos a}+1right) = dleft(frac 1{cos a}-1right)
          r = dfrac{1-cos a}{1+cos a}
          $$



          If $a=30°$, then $r = (7-4sqrt 3)d approx 0.0718 d$.



          enter image description here






          share|cite|improve this answer











          $endgroup$



          If radius of green circle is $r$, then for length $OD$:
          $$
          OD = OB+BC+CD,\
          frac d{cos a} = d + r + frac r{cos a},\
          rleft(frac 1{cos a}+1right) = dleft(frac 1{cos a}-1right)
          r = dfrac{1-cos a}{1+cos a}
          $$



          If $a=30°$, then $r = (7-4sqrt 3)d approx 0.0718 d$.



          enter image description here







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Jan 31 at 17:23

























          answered Jan 31 at 17:11









          Vasily MitchVasily Mitch

          2,6791312




          2,6791312












          • $begingroup$
            This is mind blowing, I quickly finished off the design work after sizing the green circle correctly, and I'm now returning to try and get my head round the equation. I'm incredibly grateful for the help, thank you @vasily-mitch
            $endgroup$
            – morgyface
            Jan 31 at 18:49










          • $begingroup$
            Glad to help. You might refresh basic trigonometry in a right triangle and notice the similarity between small red triangle and big $OAD$
            $endgroup$
            – Vasily Mitch
            Jan 31 at 18:57


















          • $begingroup$
            This is mind blowing, I quickly finished off the design work after sizing the green circle correctly, and I'm now returning to try and get my head round the equation. I'm incredibly grateful for the help, thank you @vasily-mitch
            $endgroup$
            – morgyface
            Jan 31 at 18:49










          • $begingroup$
            Glad to help. You might refresh basic trigonometry in a right triangle and notice the similarity between small red triangle and big $OAD$
            $endgroup$
            – Vasily Mitch
            Jan 31 at 18:57
















          $begingroup$
          This is mind blowing, I quickly finished off the design work after sizing the green circle correctly, and I'm now returning to try and get my head round the equation. I'm incredibly grateful for the help, thank you @vasily-mitch
          $endgroup$
          – morgyface
          Jan 31 at 18:49




          $begingroup$
          This is mind blowing, I quickly finished off the design work after sizing the green circle correctly, and I'm now returning to try and get my head round the equation. I'm incredibly grateful for the help, thank you @vasily-mitch
          $endgroup$
          – morgyface
          Jan 31 at 18:49












          $begingroup$
          Glad to help. You might refresh basic trigonometry in a right triangle and notice the similarity between small red triangle and big $OAD$
          $endgroup$
          – Vasily Mitch
          Jan 31 at 18:57




          $begingroup$
          Glad to help. You might refresh basic trigonometry in a right triangle and notice the similarity between small red triangle and big $OAD$
          $endgroup$
          – Vasily Mitch
          Jan 31 at 18:57


















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