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

Options

A. `4pir^(2)`
B. `6pir^(2)`
C. `3pir^(2)`
D. `8pir^(2)`

Answer

A

Explanation

Because curved surfce area of a hemisphere is `2pir^(2)` and here, we joint two solid hemispheres along their bases of radius r, form which we get solid sphere. Hence, the curved surface area a new solid `= 2 pi r^(2) + 2pir^(2) = 4pir^(2)`