Question

The angle of elevation of the top of a building from the foot of a tower is ${30}^{\circ }$. The angle of elevation of the top of the tower from the foot of the building is ${60}^{\circ }$. If the tower is 60 m high, find the height of the building.

Answer 1

Given height of tower CD = 60 m
Let the height of the building, AB = h
In right angled triangle BDC,

∴ h = 20 m
Thus the height of the building is 20 m.