Question

Find the length of the arc of a circle of diameter 42 cm which subtends an angle of 60${}^{\circ }$ at the centre.

Answer 1

D=42cm
r=$\frac{1}{2}$d
r = $\frac{1}{2}$ $\times$ 42
r=21cm
θ=60°
l= $\frac{\theta }{360°}$×2πr
l= $\frac{60°}{360°}$×2×$\frac{22}{7}$ ×21
l=$\frac{1}{6}$×2×22×3
l=$\frac{132}{6}$
l=22cm
the length of an arc is 22cm