Hello, decoy808!

We have: .The question comes in 3 parts. I have done parts (i), (ii).

(ii) If the roots of a cubic equation are:

determine the cubic expression, by expansion, with these roots.

Multiply [1]. [2] and [3]: .

Therefore: .

We have: .(iii) in part (ii) of this question, where is measured in radians.

Determine the values of that satisfy the roots, given that

And we have three equations to solve:

. .

. .

. .

. . . .