Two vertical poles are 150 m apart and the height of one is three times that of other. If from the middle point of the line joining their feet, an observer finds the angles of elevation of their tops to be complementary, then the height of the shorter pole (in meters) is:
- (A)25
- (B)
- (C)30
- (D)✓ Correct
Answer: (D)
Solution
Let the height of the shorter pole be meters, so the taller pole has height meters. The poles are 150 m apart, so the observer at the midpoint is 75 m from each pole.
Let the angle of elevation to the shorter pole be . Then the angle of elevation to the taller pole is (complementary).
From the shorter pole:
From the taller pole:
Since :
meters
Let the angle of elevation to the shorter pole be . Then the angle of elevation to the taller pole is (complementary).
From the shorter pole:
From the taller pole:
Since :
meters
JEE Main · 2021 · 24 Feb 2021 · Shift 1 · Single correct option