Answer
Please see image.
Sample alternative polar coordinates:
$(3,\displaystyle \frac{5\pi}{2})$, $(-3, \displaystyle \frac{7\pi}{2})$
.
Work Step by Step
Draw the terminal side of the angle $\displaystyle \frac{\pi}{2}$ in standard position (blue, solid line).
$r=$3 is positive,
so the point P will lie on the terminal side of the angle (blue dashed),
3 units from the pole (origin).
Valid angles are also $\displaystyle \frac{\pi}{2}+2k\pi$ with positive r,
and $\displaystyle \frac{\pi}{2}+(2k+1)\pi$ with negative r ( k any integer).
So with k=1,
$(3,\displaystyle \frac{5\pi}{2})$ and $(-3, \displaystyle \frac{7\pi}{2})$ are polar coordinates representing the same point