# How do you write the trigonometric form into a complex number in standard form 3(cos120+isin120)?

Jan 21, 2017

The answer is $= - \frac{3}{2} + i \frac{3 \sqrt{3}}{2}$

#### Explanation:

$\cos 120 = - \frac{1}{2}$

$\sin 120 = \frac{\sqrt{3}}{2}$

Therefore,

$3 \left(\cos 120 + i \sin 120\right) = 3 \cdot \left(- \frac{1}{2} + i \frac{\sqrt{3}}{2}\right)$

$= - \frac{3}{2} + i \frac{3 \sqrt{3}}{2}$