If we cut a sphere through its center, we get two equal parts. Each part is called a hemisphere.
For a hemisphere of radius r:
1. Curved Surface Area (C.S.A) = 2πr²
2. Total Surface Area (T.S.A) = 3πr²
Note: Total Surface Area includes the curved area (2πr²) plus the flat circular base area (πr²), which is also called the plain surface area.