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Question
CBSEENMA10008806

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

equals open square brackets open parentheses 2 space straight x space 22 over 7 space straight x space 7 close parentheses open parentheses 7 space plus space 6 close parentheses close square brackets space cm squared

= (44 x 13) cm2
= 572 cm2.