basically i need to convert the following parametric equation: x=a cos (T) + b cos (T/2) y=a sin (T) + b sin (T/2); where a and b are coefficients to cartesian form: y = f(x) i need it in that form so i can do calculus analysis for an improved engine design i hope to develop. thanks in advance for any help. ps. if it helps any its a graph of an epitrochoid. so ive read that it may be impossible to solve but free brownie points to those that can!