In a circle of radius 21 cm, an arc subtends an angle of 60° at the centre. Find the length of the arc.
Radius of circle = R = 21 cm
Angle subtended by arc = 60°
Length of an arc of a sector of angle 
of a circle with radius R
= Circumference of circle × θ/360
= 
Length of arc = 2 × 22/7 × 21 × θ/360 cm = 22 cm
Length of arc = 22 cm
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