Question 12 Marks
Mayank made a bird-bath for his garden in the shape of a cylinder with a hemispherical depression at one end (see Fig.). The height of the cylinder is 1.45 m and its radius is 30 cm. Find the total surface area of the bird-bath.
(Take $\pi = \frac{22}{7}$ )
(Take $\pi = \frac{22}{7}$ )
Answer
View full question & answer→Let h be height of the cylinder, and r the common radius of the cylinder and hemisphere.
Then, the total surface area of the bird-bath = CSA of cylinder + CSA of hemisphere
$=2 \pi r h+2 \pi r^{2}=2 \pi r(h+r)$
$=2 \times \frac{22}{7} \times 30(145+30) \mathrm{cm}^{2}$
$=33000 cm^2=3.3 m^2$
Then, the total surface area of the bird-bath = CSA of cylinder + CSA of hemisphere
$=2 \pi r h+2 \pi r^{2}=2 \pi r(h+r)$
$=2 \times \frac{22}{7} \times 30(145+30) \mathrm{cm}^{2}$
$=33000 cm^2=3.3 m^2$