I have the parametric function x(t) = (1-t^2)/(1+t^2), y(t) = 2t/(1+t^2) and need to eliminate the parameter and find a Cartesian equation. I've tried to substitute t = tan u, then x(t) = cos(2u) and y(t) = tan(2u). From that I get y = sin(2x)/x. However, when I entered the original parametric function into a grapher, I get an entirely different graph. Where did I go wrong?