Trig/ Precalc? Find the product of the two complex numbers?

[finalfantasy.escape]

Find the product of the two complex numbers z1=3(cos200deg+isin200deg) and z2=5(cos240deg+isin240deg). Leave your answer in trigonometric form with 0<theta<360.

I'm confused. Can someone please explain how to solve this problem step by step? Thanks!