Rose petals, cardioids, arc length, and swept angular area
Trace polar curves r = f(θ) like multi-petaled roses and calculate enclosed sector areas using (1/2) ∫ r(θ)² dθ.
In Cartesian coordinates, area elements are rectangular dA = dx dy. In polar coordinates, rotating an increment dθ sweeps out a circular wedge of radius r and arc length r dθ, giving area dA = (1/2) r² dθ.