Example 19 - Chapter 11 Class 7 Perimeter and Area
Last updated at Dec. 6, 2021 by Teachoo
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Transcript
Example 19 The adjoining figure shows two circles with same centre. The radius of the larger circle is 10 cm and the radius of the smaller circle is 4 cm. Find: (a) the area of the larger circle Radius of larger circle = R = 10 cm Area of larger circle = 𝜋R2 = 3.14 × (10)2 = 3.14 × 100 = 314/100 × 100 = 314 cm2 ∴ Area of larger circle is 314 cm2 Example 19 (b) the area of the smaller circle Radius of smaller circle = r = 4 cm Area of smaller circle = 𝜋r2 = 3.1 (4)2 = 3.14 × 16 = 314/100 × 16 = 5024/100 = 50.24 cm2 ∴ Area of smaller circle is 50.24 cm2 Example 19 (c) the shaded area between the two circles. (π = 3.14) Shaded area = Area of larger circle − Area of smaller circle = 314 − 50.24 = 314 − 50.24/100 = (314 × 100 − 5024)/100 = (31400 − 5024)/100 = 26376/100 = 263.76 cm2 ∴ Shaded area is 263.76 cm2
