For the cardioid given parametrically as
(1)
 
(2)

the involute is given by
(3)
 
(4)

which is a mirrorimage cardioid with .
For the cardioid given parametrically as
(1)
 
(2)

the involute is given by
(3)
 
(4)

which is a mirrorimage cardioid with .
Weisstein, Eric W. "Cardioid Involute." From MathWorldA Wolfram Web Resource. https://mathworld.wolfram.com/CardioidInvolute.html