There are two base circles are equal and all on a plane parallel to and three dimensional geometric shape to it with a plane parallel to the base, then cut a circle are equal in all respects each other always base.
Base, second base is a circle congruent and down a plane parallel. When cutting the three-dimensional geometry with a plane parallel to the base. It has a circular cross-section at the base always congruent.
The two base is a circle that rate exactly and be on a plane parallel to each other. And when cutting three-dimensional geometry with plane parallel to the base. Will be cut into circles that rate exactly base.