Forces and equilibrium — practice question

In the diagram, particles $A$ and $B$ have masses $0.2\,\text{kg}$ and $0.1\,\text{kg}$ respectively. They hang beneath a horizontal ceiling from two strings, $AP$ and $BQ$, which are fixed at points $P$ and $Q$ on the ceiling. The particles are joined by a horizontal string $AB$. Angle $APQ = 45^\circ$ and $BQP = \theta^\circ$. Every string is light and inextensible. The particles are in equilibrium.