1. The problem statement, all variables and given/known data Attached question 2. Relevant equations 3. The attempt at a solution The second part of question is relatively easy, it is the first part of the question where I need help with(using arg zw = arg z + arg w to show arg z^n = n arg z). Also, is the question asking to proof de Moivre's formula with the identity arg zw = arg z + arg w? or just proof LHS=RHS?