Question

Two circles are drawn inside a big circle with the diameters2/3
and 1/3
of the
diameter of the big circle. Find the area of the shaded portion, if the length
of the diameter of the big circle is 18 cm.​

Answer 1

Answer:

It is given that, diameter of the big circle = 18 cm Radius of the big circle = 9 cm

Area of the big circle, A = πr2 = π(8)2 = 81π cm2

Let d1 = (2/3) × 18 = 12 cm r1 = 6 cm

Area of the circle, A1 = πr2 = π(6)2 = 36π cm2 d2 = (1/3) × 18 = 6 cm r2 = 3 cm

Area of the circle, A2 = πr2 = π(3)2 = 9π cm2

Area of the shaded portion = A – (A1 + A2) Area of the shaded portion = 81π – (36π – 9π) = 36π cm2