Question

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).

Answer 1

Diameter of sphere=diameter of cylinder
Radius of sphere=radius of cylinder
Height of cylinder=Diameter of sphere
Height of cylinder=2r of sphere
a) Surface area of sphere=`4pir^2`
b) Curved surface area of Cylinder=`2pirH=2pir(2r)=2pir^2`
c) ratio=`(4pir^2)/(4pir^2)=1`.