3. The length of the minute hand of a clock is 14 cm. Find the area swept by the minute hand in 5 minutes.
Solution:
Length of minute hand = radius of the clock (circle)
∴ Radius (r) of the circle = 14 cm (given)
Angle swept by minute hand in 60 minutes = 360°
So, the angle swept by the minute hand in 5 minutes = 360° × 5/60 = 30°
We know,
Area of a sector = (θ/360°) × πr2
Now, area of the sector making an angle of 30° = (30°/360°) × πr2 cm2
= (1/12) × π142
= (49/3)×(22/7) cm2
= 154/3 cm2