Q13 of 26 Page 183

On the curved surface of the axis of a globe with the length of 14 cm. radius, two circular holes are made each of which has the length of radius 0.7 cm. Let us calculate the area of metal sheet surrounding its curved surface.

Given:


Radius of globe(spherical), R = 14cm


Radius of holes, r = 0.7cm


Formula used:



Surface area of sphere = 4πR2


Area of one hole(circular) = π r2


Curved surface of remaining = Curved surface area of whole sphere – Surface area of circular holes


Surface area of remaining = 4×π×R2 - 2×(π×r2)


Surface area = 4π(14)2 – 2π(0.7)2 = 2464 – 3.08 = 2460.92 cm2


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