\begin{definition}[Definition:Curvature/Polar Form]
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:
:$\kappa = \dfrac {\paren {\map \arctan {\dfrac {r \theta'} {r'} } }' + \theta'} {\paren {r'^ + \paren {r \theta'}^2}^{1/2} }$
{{Proofread}}
\end{definition}