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From the top of a 7 m building, the angles of elevation of the top and angle of depression of the bottom of a tower across the street are 60 degrees and 45 degrees. The height of the tower is
A7 (square root of 3) m
B14 m
C7 (1 + square root of 3) m
D7 m
Answer & Solution
Correct answer: C. 7 (1 + square root of 3) m
1. Distance between buildings d from depression: tan(45) = 7/d, so d = 7.
2. Height above 7 m: tan(60) = h2/7, so h2 = 7 (square root of 3).
3. Total tower height = 7 + 7 (square root of 3) = 7 (1 + (square root of 3)) m.
_Source: NCERT Class 10 Mathematics, Ch 9 "Some Applications of Trigonometry", §9.2_
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