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Ex 11.3, 12 - The circumference of a circle is 31.4 cm. Find radius

Ex 11.3, 12 - Chapter 11 Class 7 Perimeter and Area - Part 2

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Ex 11.3, 12 The circumference of a circle is 31.4 cm. Find the radius and the area of the circle? (Take Ο€ = 3.14) Radius = r = ? Given, Circumference = 31.4 cm 2πœ‹r = 31.4 2 Γ— 3.14 Γ— r = 31.4 r = 31.4/(2 Γ— 3.14) r = 314/10 Γ— 100/(2 Γ— 314) r = 1/10 Γ— 100/(2 Γ— 1) r = 10/2 r = 5 cm Now, Area of circle = πœ‹r2 = 3.14 (5)2 = 3.14 Γ— 25 = 314/100 Γ— 25 = 314/4 = 157/2 = 78.5 cm2 ∴ Radius of circle is 5 cm & it’s area is 78.5 cm2

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