Hi there....

This is what is given:

x= r(cosu+isinu) andy= t(cosv+isinv)

I am being asked to:

(1) Prove that the modulus of (xy) is the product of their moduli, showing each step.

(2) Prove that the amplitude of (xy) is the sum of their amplitudes, showing each step.

i need a starting point, desperately. This one is completely throwing me for a loop. Thanks!