Circle Pedal Curve

The pedal curve of a unit circle with parametric equation

			(1)
			(2)

with pedal point is

			(3)
			(4)

The pedal curve with respect to the center is the circle itself (Gray 1997, pp. 119 and 124-135).

If the pedal point is taken on the circumference (and in particular at the point ), the pedal curve is the cardioid

			(5)
			(6)

and otherwise is a limaçon.