Find support function of the involutes of circles












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So I have a problem on differential geometry that I am trying to work through.



Determine the support function of the involutes of a circle. Hint: To avoid computations, use the prior exercises.



In the prior exercises I found that if $n(phi)=(cos(phi), sin(phi))$, then $c(phi)=n'(phi)-n(phi)$ parameterizes a circle of radius $sqrt{2}$ centered at the origin. I also found that the evolute is $eta(phi)=h'(phi)n'(phi)-h''(phi)n(phi)$ where $h(phi)$ is the support function.



So I know that the evolute of the involute of a curve $c(t)$ is $c(t)$. And I think that if the support function is a constant, then the curve is a circle but I am not sure how to demonstrate this.










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    0












    $begingroup$


    So I have a problem on differential geometry that I am trying to work through.



    Determine the support function of the involutes of a circle. Hint: To avoid computations, use the prior exercises.



    In the prior exercises I found that if $n(phi)=(cos(phi), sin(phi))$, then $c(phi)=n'(phi)-n(phi)$ parameterizes a circle of radius $sqrt{2}$ centered at the origin. I also found that the evolute is $eta(phi)=h'(phi)n'(phi)-h''(phi)n(phi)$ where $h(phi)$ is the support function.



    So I know that the evolute of the involute of a curve $c(t)$ is $c(t)$. And I think that if the support function is a constant, then the curve is a circle but I am not sure how to demonstrate this.










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      So I have a problem on differential geometry that I am trying to work through.



      Determine the support function of the involutes of a circle. Hint: To avoid computations, use the prior exercises.



      In the prior exercises I found that if $n(phi)=(cos(phi), sin(phi))$, then $c(phi)=n'(phi)-n(phi)$ parameterizes a circle of radius $sqrt{2}$ centered at the origin. I also found that the evolute is $eta(phi)=h'(phi)n'(phi)-h''(phi)n(phi)$ where $h(phi)$ is the support function.



      So I know that the evolute of the involute of a curve $c(t)$ is $c(t)$. And I think that if the support function is a constant, then the curve is a circle but I am not sure how to demonstrate this.










      share|cite|improve this question









      $endgroup$




      So I have a problem on differential geometry that I am trying to work through.



      Determine the support function of the involutes of a circle. Hint: To avoid computations, use the prior exercises.



      In the prior exercises I found that if $n(phi)=(cos(phi), sin(phi))$, then $c(phi)=n'(phi)-n(phi)$ parameterizes a circle of radius $sqrt{2}$ centered at the origin. I also found that the evolute is $eta(phi)=h'(phi)n'(phi)-h''(phi)n(phi)$ where $h(phi)$ is the support function.



      So I know that the evolute of the involute of a curve $c(t)$ is $c(t)$. And I think that if the support function is a constant, then the curve is a circle but I am not sure how to demonstrate this.







      differential-geometry






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      share|cite|improve this question











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      share|cite|improve this question










      asked Jan 30 at 20:27









      geoplantedgeoplanted

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