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