Forces and equilibrium — practice question

A particle $P$ with weight $21\,\text{N}$ is connected to one end of each of two light inextensible strings, $S_1$ and $S_2$, whose lengths are $0.52\,\text{m}$ and $0.25\,\text{m}$ respectively. The opposite end of $S_1$ is fixed at point A, and the opposite end of $S_2$ is fixed at point B, which lies at the same horizontal level as A. Particle P is in equilibrium, hanging $0.2\,\text{m}$ below the level of $AB$, with both strings taut (see diagram).