Polar Reciprocals: A Limaçon (no loop) and an Ellipse
Point P' traces out the pedal curve - a Limaçon - of the circle A with pedal point C inside circle A. Point P is the inverse of point P' with respect to the circle C (referred to as reciprocals). The locus of point P is an ellipse. The Limaçon and the Ellipse are polar reciprocals.