Question

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

Answer 1

Because we must include the area of the lower circle part area.

that is,if 4πr² is halved it is 2πr² but we add the area of the lower circle part,

so,2πr²+πr²=3πr²