Each face has 3 edges, and is actually an Equilateral Triangle
It has 12 Edges
It has 6 Vertices (corner points)
and at each vertex 4 edges meet
And for reference:
Surface Area = 2 × √3 × (Edge Length)2
Volume = (√2)/3 × (Edge Length)3
It is called an octahedron because it is a polyhedron that has 8 (octa-) faces, (like an octopus has 8 tentacles)
If you have more than one octahedron they are called octahedra
Instructions: In "spin" mode it freely spins and will respond to your mouse. In "drag" mode it stops spinning and you can use your mouse to move it. If you cannot see the animation at all, you will need to install "Flash Player".
When we say "octahedron" we often mean "regular octahedron" (in other words all faces are the same size and shape), but it doesn't have to be - this is also an octahedron, even though all faces are not the same.. (But it may be better to call it a hexagonal prism).
8-Sided Dice? Yes! An octahedron that has 8 equal faces has an equal chance of landing on any face.
In fact, you can make fair dice out of all of the Platonic Solids.