Example 19 - Chapter 11 Class 7 Perimeter and Area
Last updated at Dec. 12, 2018 by Teachoo
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
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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.