- A regular tetrahedron is a tetrahedron in which all four faces are equilateral triangles. In other words, all of its faces are the same size and shape (congruent) and all edges are the same length. A convex polyhedron in which all of its faces are equilateral triangles is the deltahedron. There are eight convex deltahedra, one of which is the regular tetrahedron.
- Annihilationism (Wikipedia)
In Christianity, annihilationism (also known as extinctionism or destructionism) is the belief that after the Last Judgment, all damned humans and fallen angels including Satan will be totally destroyed, cremated, and their consciousness extinguished rather than suffering forever in Hell. Annihilationism stands in contrast to both the belief in eternal torment and to the universalist belief that everyone will be saved. However, it is also possible to hold to a partial annihilationism, believing unsaved humans to be obliterated or cremated, but demonic beings to suffer forever.