(a)[3]
On an Argand diagram, shade the set of points representing complex numbers $z$ that satisfy the inequalities $-\frac{1}{3}\pi \leq \arg(z - 1 - 2i) \leq \frac{1}{3}\pi$ and $\Re z \leq 3$.
(b)[2]
Calculate the minimum value of $\arg z$ for points in the region from part (a). Give your answer in radians correct to 3 decimal places.