Find the equivalent rectangular equation:

$\displaystyle x=sec(t)$

$\displaystyle y=cos(t)$

$\displaystyle \frac{-\pi}{2}\le t \le\frac{\pi}{2}$

Also, do circle/elliptical parameters always remain between $\displaystyle 0\le y \le 2\pi$??? It seems like they do but I feel I am not seeing the whole picture in gestalt.