It can also be called a rectified tetrahedron or tetratetrahedron, as it can be made by truncating a tetrahedron to the midpoints of the edges. The Higher Dimensions wiki sometimes calls this shape an Aerohedron, from aero- referring to a cross polytope and -hedron referring to three dimensions. It is possible to have a different number of triangles at the vertex of a regular solid.Jonathan Bowers calls the octahedron an Oct, a shortened form of its name. Other regular solids with triangular faces?Īn octahedron has four triangles at each vertex (corner). Spinels are red gem stones, often mistaken for rubies.Ĭlick on Move or Backwards to make octahedron move and Stop to stop it. Octahedra happen in crystals as well as cubes. It must only be bigger by a very small amount, or it will rattle. Then the bigger one could fit over the smaller one. Perhaps you could make two octahedra, each with one side removed and one bigger than the other.

You need to think how to make it into a box with a lid. However, if you lay it flat on one face, then it has not only a flat bottom but a flat top as well. You usually think of an octahedron on its point, as this makes its shape obvious. Octahedra are not usually used as packaging! But in fact an octahedron makes an attractive box. Print it out, stick it on thin card, score along the lines and fold them, form the shape, then stick it together with small amounts of glue.įor more details, see the notes for the net of a cube. These are hard to work out round the edge, but if five or six triangles are together, you know that something is wrong. There are also four triangles round a point. Of course, for an octahedron, you must have eight triangles in the net. There are eleven correct nets, and they will change colour as you click on them. See if you can find all the nets for an octahedron below. It can look like two pyramids or, from the top, it can look like a star of David. How many vertices (corners) and edges are there? See Euler's formula.Īn octahedron can look different from different angles. Since it just shows the edges, you can see through the model, which means that you can count the vertices and edges easier. This model (left) was made from a kit with magnetic connections. You can tell from its name that it has eight faces (similar to an octagon, which is a flat shape with eight angles). We saw that you cannot make a polyhedron with four squares meeting at each point, but you can do it with four triangles. Other regular solids with triangular faces?Ī tetrahedron has three faces meeting at each point, similar to a cube.

Octahedron vertices