Question

In a circle of a radius 21 cm, an arc subtends an angle of ${60}^{\circ }$ at the centre. Find the length of the arc.

Answer 1

Radius (r) of circle = 21 cm

Angle subtended by the given arc = 60°

Length of an arc of a sector of angle θ = $\frac{\theta }{{360}^o}$ $\times$ 2$\pi$r

Length of arc ACB ​​​​​= $\frac{{60}^o}{{360}^o}$ $\times$ 2 $\times$ $\frac{22}{7}$$\times$ 21

= $\frac{22}{7}$ $\times$ 2 $\times$22 $\times$ 3

= 22 cm