Question

How do you multiply `(-2-9i)(-3-6i)` in trigonometric form?

Answer 1

-48 +39i

Explanation:

distribute the brackets using FOIL

(-2 -9i )(-3 - 6i) `= 6 + 12i + 27i + 54i^2`

[Note : `i^2 = (sqrt-1)^2 = -1`]

hence `6+ 12i + 27i + 54i^2 = 6 + 39i - 54 = - 48 + 39i`