Question

The angle of elevation of the top of an unfinished tower at a point distance 80 m from its base is 30°. How much higher must the tower be raised so that its angle of elevation at the same point may be 60°?

Answer 1

Let AB be the unfinished tower and C be the top of the tower when finished , Let P be a point 80 m from the foot A. 

In triangle BAP,

Therefore , the tower must be raised by (138.56 - 46.19) m = 92.37m