Question

How do I solve 2 parts 2?

Answer 1

2 i) use Euler's identity e^iA = cos(A) + i sin(A)

2 ii) use the result from 2 i) you want an angle such that cos A = 1/2, and n=2
this gives two factors which can be factored as a difference of squares: (x^2 - y^2)= (x+y)(x-y)