[tex]\bf \begin{array}{rlclll}
(-5&,&-180^o)\\
\uparrow &&\uparrow \\
r&&\theta
\end{array}\quad
\begin{cases}
x=rcos(\theta )\\
\qquad -5\cdot cos(-180^o)\\
\qquad -5\cdot -1\\
\qquad 5\\
----------\\
y=rsin(\theta )\\
\qquad -5\cdot sin(-180^o)\\
\qquad -5\cdot 0\\
\qquad 0
\end{cases}\implies (5,0)[/tex]
