Trigonometrymedium · Past Paper
From a point P on the ground, the angle of elevation of the top of a 10 m tall building is 30°. A flag is hoisted at the top. The angle of elevation of the top of the flag is 45°. Find the length of the flag.
A10(√3-1) m
B10(1-1/√3) m
C10 m
D5 m
✓ Correct Answer: B — 10(1-1/√3) m
Distance d = 10/tan 30 = 10√3. Total height = 10√3 * tan 45 = 10√3. Flag = 10√3 - 10 = 10(√3-1). Wait, 10√3 is distance. Total height H = d*tan(45) = 10√3. Flag = 10√3 - 10.
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