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Two circles are drawn inside a big circle with diameters 2/3rd and 1/3rd of the diameter of the big circle as shown in Fig. Find the area of the shaded portion, if the length of the diameter of the circle is 18 cm. |
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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 |
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