# What is the Cartesian form of (-9,(3pi )/4)?

Dec 23, 2016

The answer is $= \left(9 \frac{\sqrt{2}}{2} , - 9 \frac{\sqrt{2}}{2}\right)$

#### Explanation:

We apply the equations to go from polar coordinates $\left(r , \theta\right)$ to cartesian coordinates $\left(x , y\right)$

$x = r \cos \theta$

$y = r \sin \theta$

Therefore,

$x = - 9 \cdot \cos \left(\frac{3 \pi}{4}\right) = - 9 \cdot - \frac{\sqrt{2}}{2} = 9 \frac{\sqrt{2}}{2}$

$y = - 9 \sin \left(\frac{3 \pi}{4}\right) = - 9 \cdot \frac{\sqrt{2}}{2} = - 9 \frac{\sqrt{2}}{2}$