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Question:

Find the surface area of a sphere of radius (i) 10.5cm (ii) 5.6cm (iii) 14cm

Solution:

(i) r = 10.5cm
SA = 4πr² = 4 × 22/7 × 10.5 × 10.5 = 88 × 15 × 105/100 = 1386cm²
(ii) r = 5.6cm
SA = 4πr² = [4 × 22/7 × (5.6)²]cm² = [88/7 × 5.6 × 5.6]cm² = 394.24cm²
(iii) r = 14cm, SA = 4πr² = 4 × 22/7 × 14 × 14 = 2464cm²