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The angle of elevation of the top of a building from the foot of a tower is 30 degrees and the angle of elevation of the top of the tower from the foot of the building is 60 degrees. If the tower is 50 m high, the height of the building is
A50/3 m
B50 m
C150 m
D50 (square root of 3) m
Answer & Solution
Correct answer: A. 50/3 m
1. tan(60) = 50/d gives d = 50/(square root of 3) (distance between bases).
2. tan(30) = b/d, where b is building height.
3. b = d × tan(30) = (50/(square root of 3)) × (1/(square root of 3)) = 50/3 m.
_Source: NCERT Class 10 Mathematics, Ch 9 "Some Applications of Trigonometry", §9.2_
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