A sphere has been defined earlier as the set of points in space that are equidistant from a fixed point called the center. If a plane cuts a sphere through the center, the circle so obtained is called the great circle. In our study, we deal with the great circle of the sphere. We may also obtain the small circle if a plane cuts the sphere and it does not contain the center of the sphere.
(1) Volume = 4/3 πr3
(2) Total surface area = 4 times the area of a circle
Total surface area = 4πr2
(3) Total surface area of a hemisphere
Total surface area of hemisphere = 3πR2
(4) Total surface area of a shell,
let outer radius = R,
inner radius = r
= 1/2 × Outer surface area + 1/2 × Inner surface area + Area of the ring
Total surface area of shell = π(3R2 + r2)
