Area and volume of the sphere
1. Sphere parts
In the picture we see several spherical objects: a globe, a balloon and a ball.
In the sphere, all points of the surface are at the same distance of an inner point called center.
The radius of the sphere is any line segment joining the center to a point on the spherical area. All radius of the sphere are equal.
Diameter is any segment that passes through the center and connects two points on the surface.
Look at this figure and answer: