# How do you convert (−2, −9) into polar form?

Feb 6, 2017

$\sqrt{85} \left[\cos \left(\pi + \arctan 4.5\right) + i \sin \left(\pi + \arctan 4.5\right)\right]$

#### Explanation:

$- 2 = r \cos t , - 9 = r \sin t$

$\tan t = \frac{9}{2}$

$t = \pi + \arctan 4.5$
Where we add $\pi$ because our point is at 3rd quadrant.

${2}^{2} + {9}^{2} = {r}^{2} = 85$