2022 · Q54
The angle of elevation of the top of a tower of height x metre from a point on the ground is found to be 60°. By going y metre away from that point, it becomes 30°. Which one of the following relations is correct?
Elementary MathematicsTrigonometry
- Ax = y
- B2x = 3y
- C2x = √3y
- D2y = √3x
Explanation
tan60° = x/d and tan30° = x/(d+y) give d = x/√3; then y = x√3-x/√3 = 2x/√3, i.e. 2x = √3y. Hence the keyed option is C.