Radius of curvature
= Radius of curvature
{title2=$\rho=1/\kappa$}
{wiki}
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.