Question

If two solid hemispheres of same base diameter 7 cm are joined together along their bases, then find the curved surface area of this new solid.​

Answer 1

Answer:

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.

Answer 2

Answer:

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

Or

We know that,

Curved surface area of a hemisphere =2πr

2

So, when two solids hemispheres of same base radius are joined together along their bases, then

Curved surface area of newly formed solid sphere=2×2πr

2

=4πr

2

Hence, A is the correct option.