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From a point on the ground 60 m from the foot of a building, the angle of elevation of the top is 30 degrees. The height of the building is
A60/(square root of 3) m
B60 (square root of 3) m
C30 m
D20 (square root of 3) m
Answer & Solution
Correct answer: D. 20 (square root of 3) m
1. tan(30) = h / 60.
2. h = 60 × tan(30) = 60 × 1/(square root of 3) = 60/(square root of 3).
3. Rationalize: h = 60 (square root of 3)/3 = 20 (square root of 3) m.
_Source: NCERT Class 10 Mathematics, Ch 9 "Some Applications of Trigonometry", §9.2_
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