Abstrakt
Graphic constructions of real three-dimensional quadrics as cuts of four-dimensional cones with three-dimensional spaces are described. All the constructions are presented on interactive models in GeoGebra 5 with use of descriptive geometry methods, which are based on a visualization technique of double orthogonal projection of the four-dimensional space onto two perpendicular three-dimensional spaces.
We visualize a four-dimensional cone, its cutting 3-space and the section simultaneously in one figure. For detailed reasoning and verifications, the constructions are also supported analytically.