Question
A solid sphere of diameter 4.9 cm is cut into two equal
halves. What will be the increase in its total surface area?Solution
Given: Diameter = 4.9 cm Radius = 4.9/2 = 2.45 cm Total surface area of sphere = 4 × 22/7 × 2.45 × 2.45 = 75.46 cm2 if sphere is cut into two equal halves, then, it becomes two hemispheres of radius 2.45 cm. Total surface area of the 2 equal hemi spheres = 2 × 3πr2 => 2 × 3 × 22/7 × 2.45 × 2.45 = 113.19 cm2 The increase in total surface area = 113.19 – 75.46 = 37.73 cm2
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