Using Line Element to find out length of a curve on a circle












1












$begingroup$


Let us denote a unit sphere by $S$ and assume that $gamma: [0,1] rightarrow S$ is a continuos and differentiable function.



Let us parametrize $S$ by spherical coordinates $(a, b)$ and assume the riemannian metric on $S$ is given by $mathrm{d}s^2=mathrm{d}a^2 + sin^2(a)mathrm{d}b^2$.



To find out the length of $gamma$ we need to evaluate $int_{0}^1mathrm{d}svert_{gamma(t)},mathrm{d}t$.



Question



Circle is also a Riemannian manifold.
Can we calculate the length of a curve on a unit circle using above formula ?
What is the $ds^2$ for a unit circle that is parameterized is only by one parameter $a$?










share|cite|improve this question









$endgroup$

















    1












    $begingroup$


    Let us denote a unit sphere by $S$ and assume that $gamma: [0,1] rightarrow S$ is a continuos and differentiable function.



    Let us parametrize $S$ by spherical coordinates $(a, b)$ and assume the riemannian metric on $S$ is given by $mathrm{d}s^2=mathrm{d}a^2 + sin^2(a)mathrm{d}b^2$.



    To find out the length of $gamma$ we need to evaluate $int_{0}^1mathrm{d}svert_{gamma(t)},mathrm{d}t$.



    Question



    Circle is also a Riemannian manifold.
    Can we calculate the length of a curve on a unit circle using above formula ?
    What is the $ds^2$ for a unit circle that is parameterized is only by one parameter $a$?










    share|cite|improve this question









    $endgroup$















      1












      1








      1


      0



      $begingroup$


      Let us denote a unit sphere by $S$ and assume that $gamma: [0,1] rightarrow S$ is a continuos and differentiable function.



      Let us parametrize $S$ by spherical coordinates $(a, b)$ and assume the riemannian metric on $S$ is given by $mathrm{d}s^2=mathrm{d}a^2 + sin^2(a)mathrm{d}b^2$.



      To find out the length of $gamma$ we need to evaluate $int_{0}^1mathrm{d}svert_{gamma(t)},mathrm{d}t$.



      Question



      Circle is also a Riemannian manifold.
      Can we calculate the length of a curve on a unit circle using above formula ?
      What is the $ds^2$ for a unit circle that is parameterized is only by one parameter $a$?










      share|cite|improve this question









      $endgroup$




      Let us denote a unit sphere by $S$ and assume that $gamma: [0,1] rightarrow S$ is a continuos and differentiable function.



      Let us parametrize $S$ by spherical coordinates $(a, b)$ and assume the riemannian metric on $S$ is given by $mathrm{d}s^2=mathrm{d}a^2 + sin^2(a)mathrm{d}b^2$.



      To find out the length of $gamma$ we need to evaluate $int_{0}^1mathrm{d}svert_{gamma(t)},mathrm{d}t$.



      Question



      Circle is also a Riemannian manifold.
      Can we calculate the length of a curve on a unit circle using above formula ?
      What is the $ds^2$ for a unit circle that is parameterized is only by one parameter $a$?







      riemannian-geometry






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Dec 30 '18 at 16:07









      Andrzej GolonkaAndrzej Golonka

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