Question

A man is walking towards a vertical pillar in a straight path, at a uniform speed. At a certain point A on the path, he observes that the angle of elevation of the top of the pillar is 30°. After walking for 10 min from A in the same direction, at a point B, he observes that the angle of elevation of the top of the pillar is now 60°. Then, the time taken (in minutes) by him from B to reach the pillar is

(A) 5

(B) 6

(C) 10

(D) 20

Answer 1

Correct option (A) 5

The given situation is depicted in Fig. We have

AB = x; BP = y; PQ = h

Let the speed of man be u. Therefore,