In the given figure, three sectors of a circle of radius 7 cm, making angles of 60°, 80° and 40° at the centre are shaded. Find the area of the shaded region.

Given:

Radius of circle = 7 cm


Let the sectors with central angles 80°, 60° and 40° be S1, S2, and S3 respectively.


Then, the area of shaded region = Area of S1 + Area of S2 + Area of S3 …………………….. (i)


Area of sector = × πr2


Area of S1 = × × 7 × 7


= cm2


Similarly, Area of S2 = × × 7 × 7


= cm2


and Area of S3 = × × 7 × 7


= cm2


Thus, using (i), we have


Area of shaded region = + +


=


= = 77 cm2


Hence, the area of shaded region is 77 cm2.


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