### The five Platonic solids

Regular polyhedrons are convex solids with faces that are identical regular polygons and where the same number of sides arrives at the vertexes. The sum of the angles around a vertex must be less than 360° so there can only be five regular solids: three formed of triangles (tetrahedron, octahedron and icosahedron), one of square faces (cube) and one formed of pentagons (dodecahedron).