Height And Distance

A tower PQ stands on a horizontal ground with base \(Q\) on the ground. The point \(R\) divides the tower in two parts such that \(Q R=15 \mathrm{~m}\). If from a point \(A\) on the ground the angle of elevation of \(R\) is \(60^{\circ}\) and the part \(P R\) of the tower subtends an angle of \(15^{\circ}\) at \(A\), then the height of the tower is :