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The shadow of a 30 m tall tower becomes 30/(square root of 3) m shorter when the sun rises from a 30 degree to a 60 degree elevation. The original shadow length at 30 degrees is
A20 (square root of 3) m
B30 (square root of 3) m
C20 m
D10 (square root of 3) m
Answer & Solution
Correct answer: B. 30 (square root of 3) m
1. At 30 degrees: shadow = 30/tan(30) = 30 (square root of 3).
2. At 60 degrees: shadow = 30/tan(60) = 30/(square root of 3).
3. Original (30 deg) = 30 (square root of 3) m.
_Source: NCERT Class 10 Mathematics, Ch 9 "Some Applications of Trigonometry", §9.2_
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