Hart's inversor is a linkage which draws the inverse of a given curve. It can also convert circular to linear motion. The rods satisfy and , and , , and remain collinear while is kept parallel to . This condition holds automatically if .
Coxeter (1969, p. 428) shows that if , then
More things to try:
Weisstein, Eric W. "Hart's Inversor." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/HartsInversor.html