The Total solution for NCERT class 6-12
Solution:
Radius of the larger circle, R = 21 cm
Radius of the smaller circle, r = 7 cm
Angle made by sectors of both concentriccircles = 30┬░
Area of the larger sector = (30┬░/360┬░)├Ч╧АR2┬аcm2
= (1/12)├Ч(22/7)├Ч212┬аcm2
= 231/2cm2
Area of the smaller circle = (30┬░/360┬░)├Ч╧Аr2┬аcm2
= 1/12├Ч22/7├Ч72┬аcm2
=77/6 cm2
Area of the shaded region = (231/2) тАУ (77/6)cm2
= 616/6 cm2┬а= 308/3cm2