Ball

A ball is a body that consists of all points of space that are at a distance no greater than a given one from a given point. This point is called the center of the ball , and this distance is the radius of the ball .
The boundary of the ball is called a spherical surface , or sphere . Thus, the points of the sphere are all points of the ball that are removed from the center by a distance equal to the radius. Any segment connecting the center of the ball to the point of the ball surface is also called the radius.
The segment connecting the two points of the ball surface and passing through the center of the ball is called the diameter