If the length of the minute hand of a clock is 12 cm, the area of swep

1.	If the length of the minute hand of a clock is 12 cm, the area of swept byit in 15 minutes is(A) 5 sqcm (B) 2 sqcm (C) 792/7sq.cm (D) 0
Answer» In 60 minutes, the minutes hand covers 360 degrees. or angle of 2π or the full circle. In one minute it sweeps an angle of 2π / 60 or 1/60th of the area of full circle. Area of the sector it sweeps in one minute =π r² / 60 =π * 12² / 60 = 7.54 cm² Hence in 15 minutes7.54*15=113.1cm^2=792/7cm^2option 3

If the length of the minute hand of a clock is 12 cm, the area of swept byit in 15 minutes is(A) 5 sqcm (B) 2 sqcm (C) 792/7sq.cm (D) 0

Answer»

In 60 minutes, the minutes hand covers 360 degrees. or angle of 2π or the full circle.

In one minute it sweeps an angle of 2π / 60 or 1/60th of the area of full circle.

Area of the sector it sweeps in one minute =π r² / 60 =π * 12² / 60 = 7.54 cm²

Hence in 15 minutes7.54*15=113.1cm^2=792/7cm^2option 3