Of the stauraxonia isopola we have, for instance, the double pyramids, one of the simplest forms of the octahedron.
Combinations of the cube and octahedron are shown in figs. 6-8.
Two of these generate the cube and the octahedron; five of these generate the dodecahedron and the icosahedron.
It may be derived from the octahedron by suppressing the alternate faces.
That for the tetrahedron has 12 for its order, for the cube (or octahedron) 24, and for the icosahedron (or dodecahedron) 60.
The other piece of money in circulation was octahedron in shape or form.
These give the solid angles of the tetrahedron, the octahedron and the icosahedron.
It is not difficult for a class to find the relative areas of the cube and the inscribed tetrahedron and octahedron.
Inscribe an octahedron in Venus, the circle inscribed in it will be Mercury.
A cube may be inscribed in an octahedron, its vertices being at the centers of the faces of the octahedron.