(a)[3]
Find $\frac{u^2}{w}$, and write your answer in the form $re^{i\theta}$, where $r > 0$ and $-\pi < \theta \leq \pi$. State the exact values of $r$ and $\theta$.
(b)[1]
State the smallest positive integer $n$ for which both $\operatorname{Im}\, w^n = 0$ and $\operatorname{Re}\, w^n > 0$.