The regular polyhedra are five
A way to see why there are only 5 regular polyhedra: we can use equilateral triangles as faces of a polyhedron by putting 5, 4 or 3 triangles around each vertex (as we can see in the picture: in this case we get the tetrahedron).
The image has been realized for the exhibition Simmetria, giochi di specchi - Symmetry, playing with mirrors.
© matematita
The image belongs to the sections...:
All together (3D geometry)