Question

The length of the minute hand of a clock is 21 cm. The area swept by the minute hand in 10 minutes is [CBSE 2012]
(a) 231 cm²
(b) 210 cm²
(c) 126 cm²
(d) 252 cm²

Answer 1

Angle subtends by the minute hand in 1 minute = 6^∘
∴ Angle subtends by the minute hand in 10 minutes = 60^∘
Now,
Area of the sector$=\frac{\mathrm{\theta }}{360°}\mathrm{\pi }{r}^2=\frac{60°}{360°}\times \frac{22}{7}{\left(21\right)}^2=231{\mathrm{cm}}^2$
Hence, the correct answer is option (a).