If $\mathrm{P}( \mathrm{\theta } )$ is a point  on the ellipse  $\frac{{\mathrm{x}}^2}{{\mathrm{a}}^2}+\frac{{\mathrm{y}}^2}{{\mathrm{b}}^2}=1 (\mathrm{a} > \mathrm{b})$ then its corresponding point is

$\mathrm{P}\left(\mathrm{\theta }\right)=(\mathrm{acos\theta }, \mathrm{bsin\theta }) be point on the ellipse \frac{x^2}{a^2}+\frac{y^2}{b^2}=1$

It's  corresponding point $=(\mathrm{acos\theta }, \mathrm{asin\theta })$