The perimeter of the sector of a circle of radius 21 cm which subtends an angle of $60^{\circ}$ at t

Question

The perimeter of the sector of a circle of radius 21 cm which subtends an angle of $60^{\circ}$ at the centre of circle, is:\

Professor PC Thomas Classes · Answer

(c): Given radius $=21 \mathrm{~cm}, 	heta=60^{\circ}$\ Length of arc of the sector of a circle $(l)=\frac{	heta}{360^{\circ}} 	imes 2 \pi r$\ $=\frac{60^{\circ}}{360^{\circ}} 	imes 2 	imes \frac{22}{7} 	imes 21=22 \mathrm{~cm}$\ ∴ Perimeter of sector of circle $=2 r+1=2 	imes 21+22$ $$ =42+22=64 \mathrm{~cm} $$