ball, TORus AND SPHERICAL SURFACES
The external surface of a ball is called the sphere. Each point of the sphere is within the same distance from the centre which is sphere radius.
As the distance to the axis of revolution decreases, the ring torus becomes a horn torus, then a spindle torus, and finally generates into a sphere.
Compare images of different shapes of rotation and answer a question - is there a figure among them formed by rotation of a circle round its tangent?