## Precalculus (6th Edition) Blitzer

$sin(t)$, $cos(t)$, $sin^2t+cos^2=1$
With the given pair of parametric equations, we can isolate $sin(t)$ and $cos(t)$, use the identity $sin^2t+cos^2=1$, and add the square of the two isolated equations to eliminate the parameter $t$.