[填空题]
$\text { Points } \mathrm{A} \text { and } \mathrm{B} \text { represent the complex numbers } z_{1}=\sqrt{3}-\mathrm{i} \text { and } z_{2}=-3-3 \mathrm{i} \text { as shown on the Argand diagram below. }$
1. Find the angle A O B .$\frac{a \pi}{b}$ a = b =
2. Find the argument of $z_{1} z_{2}$ .$-\frac{a \pi}{b}$ a = b =
3. Given that the real powers of $p z_{1} z_{2}$ , for p>0 , all lie on a unit circle centred at the origin, find the exact value of p .$\frac{\sqrt{a}}{b}$ a = b =
