NTA Abhyas JEE Main2020MathematicsHeights and DistancesPractice
The angular elevation of tower C D at a point A due south of it is 60 o and at a point B due west of A , the elevation is 3 0 o . If A B = 5 k m , then the height of the tower is (where, C , B and A are on the same ground level)
Options
- A2 3 k m
- B2 6 k m
- C5 3 2 km
- D5 3 2 2 k m
Correct answer
D. 5 3 2 2 k m
Step-by-step solution
From ΔCDA ,   x = h cot 60 o = h 3 From ΔCDB ,   y = h cot 30 o = 3 h x 2 + 5 2 = y 2 (in ∆ A C B ) ⇒ h 3 2 + 5 2 = 3 h 2 ⇒ h = 5 3 2 2 k m .