(a)[2]
State the values of $\omega z_1$ and $\omega z_2$. Write each result in the form $re^{i\theta}$, where $r > 0$ and $-\pi < \theta \leq \pi$.
(b)[2]
On a sketch of an Argand diagram with origin $O$, indicate the points $A$, $B$, $C$ and $D$ to represent the complex numbers $z_1$, $z_2$, $\omega z_1$ and $\omega z_2$, respectively.
(c)[2]
State the geometric effects of multiplying $z_1$ and $z_2$ by $\omega$.