 Radius of curvature

Where a regular curve has positive curvature $\kappa$, its radius of curvature is the radius $\rho =1/\kappa$ of its osculating circle. A sharper bend has a smaller radius. At zero curvature there is no finite radius; writing $\rho =\infty$ is a limiting convention rather than an ordinary real reciprocal of zero.

The radius of curvature is a measure that describes how sharply a curve bends at a particular point. It is defined as the radius of the smallest circle that can fit through that point on the curve. In simpler terms, it's an indicator of the curvature of a curve; a smaller radius of curvature corresponds to a sharper bend, while a larger radius indicates a gentler curve.