Use the parametrization r() = ( () cos , () sin ) to show that a curve r = () in polar coordinates has

Use the parametrization r(θ) = (ƒ (θ) cos θ, ƒ (θ) sin θ) to show that a curve r = ƒ(θ) in polar coordinates has curvature

K(0) = If (0) +2f'(0) - (0)"(0)| (f(0) + f'(0))/2