Question
A vessel is in the form of a hollow hemisphere mounted by a hollow cylinder. The diameter of the hemisphere is 14 cm and the total height of the vessel is 13 cm. Find the inner curved surface area of the vessel.
Solution
Let r cm be the radius of the cylinder and h cm be the height of the cylinder, then
r = 7 cm,
and h = (13–7) cm
= 6 cm.
Let r1 cm be the radius of the hemisphere, then
r1 = 7 cm
Now,
the inner curved surface area of the vessel
= C,S.A of hemisphere
+ C,S.A of cylinder
= (2πr12 + 2 π rh) cm2
= (2 π r2 + 2 π rh) cm2 [∵ r1 = r]
= [2 π r (r + h)] cm2
= (44 x 13) cm2
= 572 cm2.