Question

Ramesh made a bird-bath for his garden in the shape of a cylinder with a hemispherical depression at one end. The height of the cylinder is 1.45 m and its radius is 30 cm. Find the total surface area of the bird-bath.

Answer 1

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

= 2πrh + 2πr²

= 2πr(h + r)

= `2 xx 22/7 xx 30(145 + 30)` cm²

= `2 xx 22/7 xx 30 xx 175` cm²

= 33000 cm²

= 3.3 m²