Question

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

(a) 21 cm (b) 22 cm (c) 18.16 cm (d) 23.5 cm

Answer 1

Radius (r) of circle = 21 cm

The angle subtended by the given arc = ${60}^o$

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

Length of arc APB $=\frac{{60}^o}{{360}^o}\times 2\times \frac{22}{7}\times 21=\frac{1}{6}\times 2\times \frac{22}{7}\times 21=22cm$