Given,
Radius of circle = 21 cm
Angle subtend by arc = 60°
= \(\frac{60π}{180}\) = \(\frac{π}{3}\) radius
Length of the arc = \(\frac{π}{3}\times21\) = 22 cm
Area of sector formed by arc = \(\frac{θ}{360}πr^2\)
= \(\frac{60}{360}\times\frac{22}7\times21\times21\)
= \(\frac{1}{60}\times\frac{22}7\times21\times21\)
= 23.1 cm2