Question

A person standing on the bank of a river, observes that the angle of elevation of the top of a tree on the opposite bank of the river is 60° and when he retires 40 m away from the tree the angle of elevation becomes 30°. The breadth of the river is

(a) 20 m

(b) 30 m

(c) 40 m

(d) 60 m

Answer 1

The correct option is (a) 20 m.

Explanation:

Let CD ( =h) be the height of the tree and BC ( =x) be the width of the river.