2017 · Q67
An aeroplane flying at a height of 300 m above the ground passes vertically above another plane at an instant when the angles of elevation of the two planes from the same point on the ground are 60° and 45° respectively. What is the height of the lower plane from the ground ?
Elementary MathematicsTrigonometry
- A100√(3)
- B100/(√(3))
- C50√(3)
- D150(√(3)+1) m
Explanation
Let the horizontal distance be d: tan60° = 300/d and tan45° = h/d, so h = 300·tan45°/tan60° = 300/√3 = 100√3 m: option A.