\begin{definition}[Definition:Center of Curvature]
Let $C$ be a curve embedded in the plane.
Let $N$ be the normal to $C$ at a point $P$.
Let $\rho$ be the radius of curvature of $C$ at $P$.
Let $Q$ be the point on $N$ which is at a distance $\rho$ from $P$ on the concave side of $C$.
$Q$ is known as the '''center of curvature''' of $C$ at $P$.
\end{definition}