# How do you multiply  (-1+2i)(3+2i)  in trigonometric form?

Dec 30, 2017

$- 7 + 4 \iota$

#### Explanation:

$\iota = \sqrt{- 1}$
So, ${\iota}^{2} = - 1$

$\left(- 1 + 2 \iota\right) \left(3 + 2 \iota\right)$

$- 3 - 2 \iota + 6 \iota - 4$

$- 7 + 4 \iota$

Simply multiply as we generally multiply polynomial by polynomial provided the rules of complex must in mind just like ${\iota}^{2} = - 1$.