[tex]\bf \begin{array}{rllll}
(-5&,&\frac{5\pi }{3})\\
\uparrow &&\uparrow \\
r&&\theta
\end{array}\qquad
\begin{cases}
x=rcos(\theta )\\
y=rsin(\theta )\\
----------\\
x=(-5)cos\left( \frac{5\pi }{3} \right)\\
\qquad -5\cdot \frac{1}{2}\\
\qquad -\frac{5}{2}\\
y=(-5)sin\left( \frac{5\pi }{3} \right)\\
\qquad -5\cdot -\frac{\sqrt{3}}{2}\\
\qquad \frac{5\sqrt{3}}{2}
\end{cases}\implies \left(-\frac{5}{2}\ ,\ \frac{5\sqrt{3}}{2} \right)[/tex]
