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13. A road which is 7m wide around a circular parkwhosecircumference is 352cm. Find the area of the road.Letr be the radius of the parkSol: |
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Answer» Circumference of a circular park= 352 mWidth of a road = 7 mCircumference = 2πr352 = 2 ×( 22/7)× r352×7 = 44rr = (352×7)/44 = 8 × 7 = 56 mInner radius of the park (r) = 56 mOuter radius of the Park including the road (R )= width + rR = 7 + 56 = 63 mR = 63 mArea of the road = π(R² - r²)= π(R+r) (R - r) [a² - b² = (a-b)(a-b)]= 22/7 (63+56)(63-56)= 22/7 × 119 × 7= 22 × 119Area of the road= 2618 m²Hence, the Area of the road is 2618 m². |
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