A piece of wire 20 cm long is bent into the form of an arc of a circle subtending an angle of 60° at its centre. Find the radius of the circle.
Arc is a part of circle that makes 60° between radii at endpoints A and B of wire.
So, it form the shape of a sector.
r = ? l = 20 cm
∴ Length of arc l = `(2 pir theta)/360^circ`
⇒ 20 cm = `(2 xx pi xx r xx 60^circ)/360^circ`
⇒ `2pir = 20 xx 6`
⇒ r = `120/(2pi) = 60/pi ` cm
Concept: Area of Circle
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