An icosahedron is a three-dimensional shape with twenty faces which makes it a polyhedron. It is one of the few platonic solids.The 1 Frequency Geodesic Dome Has 1 Edge for Each Edge of the Icosahedron. The 1 Frequency Dome has 1 Edge and 1 Triangle for each Face of the Icosahedron. The 1 Frequency Dome is an Icosahedron.