# In figure 2, two

Given two concentric circles with centre O having radii 21 cm and 42 cm.

We know that area between the circles = π (R2 – r2)

Area = (22/7) (422 – 212)

= (22/7) (1323)

= 4158 cm2

Angle subtended by the arc in the inner circle = 60°

Area of the sector in the inner circle = 231 cm2

Angle subtended by the arc in the outer circle = 60°

Area of the sector in the outer circle = 924 cm2

Area of the portion of the sector in between the circles = 924 – 231 = 693 cm2

Area of the shaded portion = Area between the circles – area of the portion in between the circles

= 4158 – 693

= 3465

The area of the shaded region is 3465 cm2.

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