Question

The total surface area of sphere is4πr2 and total surface area of hemisphere is 3πr whyThe total surface area of sphere is4πr2 and total surface area of hemisphere is 3πr why it is 3πr2 instead of 2πr2 ? Explain
it is 3πr2 instead of 2πr2 ? Explain

Answer 1

Answer:

Step-by-step explanation:

the total surface area of hemisphere is the area covered by the flat and curved surface of the hemisphere

The curved surface of the hemisphere is $2\pi r^{2}$

The flat surface under this hemisphere is a circle which has an area of $\pi r^{2}$

so the total surface area of hemisphere is $3\pi r^{2}$

whereas in a sphere there is no flat surface therefore the total surface are of a  sphere is $4\pi r^{2}$