Görbület

Az $r(t)=( x(t), y(t) )$ paraméteres görbe görbülete:

\( \kappa = \frac{ \mid r'(t) \times r''(t) \mid }{ \mid r'(t) \mid^3} = \frac{ \mid x'(t) \cdot y''(t) - y'(t) \cdot x''(t) \mid}{ \sqrt{ (x'(t))^2 + (y'(t))^2}^3} \)