Question

If 3+3i and z2=7(cos(5pi/9)+isin(5pi/9)), then z1z2=?

http://gyazo.com/d22b1a8cd08fb2eb9b4b9e39cec1e351

Answer 1

Answer choices posted above ^

Answer 2

when you multiply complex numbers (in polar form), you multiply their magnitudes and *add* their angles

Answer 3

Hm, so would I have to convert "3+3i" to polar form?

Answer 4

that would be a good first step. its mag= sqr of sum of squares
its angle is inverse tan of imag/real