Question

The minute hand of a clock is 15 cm long. Calculate the area swept by it in 20 minutes.

Answer 1

Angle inscribed by the minute hand in 60 minutes = 360°

Angle inscribed by the miniute hand in 20 minutes`=360/60xx20=120°`

We have : 

θ = 120 and r = 15 cm

∴ Required area swept by the miniute hand in 20 miniutes = Area of the sector with r = 15 cm and θ = 120°   

`= (pi"r"^2theta)/360`

`=3.14xx15xx15xx120/360`

= 235.5 cm²