The angle of elevation of the top of a tower from a point P on the ground is a. After walking a distance d towards the foot of the tower, angle of elevation is found to be b.
Let height of the tower be h and the distance between the point P and the foot of tower is x. So,
In,
In ,
Substitute value of x in above equation, we get,
Hence, option (2) is correct, i.e. .