Definition:Curvature/Polar Form

Definition
Let $C$ be a curve defined by a real function which is twice differentiable. Let $C$ be embedded in a polar plane.

The curvature $\kappa$ of $C$ at a point $P = \polar {r, \theta}$ is given by:


 * $\kappa = \dfrac {\paren {\map \arctan {\dfrac {r \theta'} {r'} } }' + \theta'} {\paren {r'^ + \paren {r \theta'}^2}^{1/2} }$

Also see

 * Equivalence of Definitions of Curvature