# How do you write the trigonometric form in complex form 4(cos((3pi)/2)+isin((3pi)/2)))?

Jan 6, 2017

The answer is $= - 4 i$

#### Explanation:

Let $z = 4 \left(\cos \left(\frac{3 \pi}{2}\right) + i \sin \left(\frac{3 \pi}{2}\right)\right)$

$\cos \left(\frac{3 \pi}{2}\right) = 0$

$\sin \left(\frac{3 \pi}{2}\right) = - 1$

Therefore,

$z = 4 \left(0 - 1 \cdot i\right)$

$z = - 4 i$