Question:
A vessel 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 surface area of the vessel.
Solution:
We have to find the inner surface area of a vessel which is in the form of a hemisphere mounted by a hollow cylinder.
Radius of hemisphere and cylinder $(r)=7 \mathrm{~cm}$
Total height of vessel $(r+h)=13 \mathrm{~cm}$
So, the inner surface area of a vessel,
$=2 \pi r(r+h)$
$=2\left(\frac{22}{7}\right)(7)(13) \mathrm{cm}^{2}$
$=572 \mathrm{~cm}^{2}$