Cayley's Sextic Evolute

The evolute of Cayley's sextic with parametrization

			(1)
			(2)

is given by

			(3)
			(4)

With parametrization

			(5)
			(6)

the evolute is given by

			(7)
			(8)

For , the evolute is defined at regular points of the original curve; the displayed formulas also extend to the singular point by a limit. This curve is a nephroid.