The ellipse x272+y252=1\displaystyle \frac{{{x}^{{2}}}}{{{7}^{{2}}}}+\frac{{{y}^{{2}}}}{{{5}^{{2}}}}={1} can be drawn with parametric equations where x(t)\displaystyle {x}{\left({t}\right)} is written in the form

x(t)=rcos(t)\displaystyle {x}{\left({t}\right)}={r}{\cos{{\left({t}\right)}}} with r =

and y(t) =