Discrete random variables — practice question

Particle $P$ has mass $0.2\,\text{kg}$ and is fastened to one end of a light inextensible string of length $0.6\,\text{m}$. The free end of that string is fixed at point $A$. $P$ is also attached to one end of a second light inextensible string of length $0.6\,\text{m}$, and the other end is fixed at point $B$ directly below. The particle travels in a horizontal circle of radius $0.3\,\text{m}$, centred at the midpoint of $AB$, with both strings remaining straight (see diagram).