# How do you find the rectangular coordinate for [3, pi/2]?

and its polar polar coordinate be $\left(r , \theta\right)$
then $x = r \cos \theta \mathmr{and} y = r \sin \theta$
here $r = 3 \mathmr{and} \theta = \frac{\pi}{2}$
$x = 3 \cdot \cos \left(\frac{\pi}{2}\right) = 3 \cdot 0 = 0$
$y = 3 \cdot \sin \left(\frac{\pi}{2}\right) = 3 \cdot 1 = 3$
So Cartesian coordinate=$\left(0 , 3\right)$