What is the easiest way for solving the question of class 9th ncert math of exercise 13.4 of math of Surface areas and Volumes chapter of question no. 2(2) Please help me for the best suggestion of this question Find the surface area of a sphere of diameter: (ii) 21cm
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Radius (r) of sphere = 21/2 = 10.5 cm
Surface area of sphere = 4πr2
= 4×(22/7)×10.52 = 1386
Surface area of a sphere is 1386 cm2
Therefore, the surface area of a sphere having diameter 21cm is 1386 cm2