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The area swept by the hour hand of length 5 cm in 4 hours is
A(50 pi)/6 sq cm
B(25 pi)/6 sq cm
C(25 pi)/3 sq cm
D5 pi/3 sq cm
Answer & Solution
Correct answer: C. (25 pi)/3 sq cm
1. In 4 hours the hour hand sweeps 4/12 × 360 = 120 degrees.
2. Area = (120/360) × pi × 5 squared = (1/3) × 25 pi = 25 pi / 3.
3. Hence (25 pi)/3 sq cm.
_Source: NCERT Class 10 Mathematics, Ch 11 "Areas Related to Circles", §11.2_
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