Question

If two solid hemispheres of same base radius r are joined together along their bases, then curved surface area of this new solid is

(a) 4πr² (b) 6πr² (c) 3πr² (d) 8πr²

Answer 1

The correct option is (a) 4πr².

Explanation:

Because curved surface area of a hemisphere is 2 w² and here, we join two solid hemispheres along their bases of radius r, from which we get a solid sphere.

Hence, the curved surface area of new solid = 2 πr² + 2 πr² = 4πr².