Q9 of 75 Page 225

A right circular cylinder just encloses a sphere of radius r (see Fig. 13.22). Find

(i) Surface area of the sphere,


(ii) Curved surface area of the cylinder


(iii) Ratio of the areas obtained in (i) and (ii)


(i) Surface area of sphere = 4πr2

(ii) Height of cylinder = r + r = 2r


Radius of cylinder = r


CSA of cylinder = 2πrh


= 2πr (2r)


= 4r2


(iii) Ratio =


= = 1


Ratio = 1: 1


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