Question

X = 5 cos t, y = 5 sin t Eliminate the perameter

Answer 1

$\bf \begin{cases} x=5cos(t)\implies \frac{x}{5}=cos(t)\\\\ cos^{-1}\left( \frac{x}{5} \right)=cos^{-1}[cos(t)]\\\\ cos^{-1}\left( \frac{x}{5} \right)=\boxed{t}\\ ----------\\ y=5sin(t)\implies y=5sin\left( \boxed{cos^{-1}\left( \frac{x}{5} \right)} \right) \end{cases}$

just a matter of substitution