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
Solution:
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 $=\frac{\theta}{360^{\circ}} \pi r^{2}=\frac{60^{\circ}}{360^{\circ}} \times \frac{22}{7}(21)^{2}=231 \mathrm{~cm}^{2}$
Hence, the correct answer is option (a).
Click here to get exam-ready with eSaral
For making your preparation journey smoother of JEE, NEET and Class 8 to 10, grab our app now.