# Octahedron

Octahedron Facts

**Notice these interesting things:**

- It has 8 Faces
- Each face is an Equilateral Triangle
- It has 12 Edges
- It has 6 Vertices (corner points)
- and at each vertex 4 edges meet
- It is one of the Platonic Solids

images/polyhedra.js?mode=octahedron

## Volume and Surface Area

**Volume** = (√2)/3 × (Edge Length)^{3}

**Surface Area** = 2 × √3 × (Edge Length)^{2}

It is called an *octahedron* because it is a polyhedron that has 8 (*octa-*) faces, (like an *octopus* has 8 tentacles)

When we have more than one octahedron they are called **octahedra**

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.

Make your own Octahedron, cut out the shape and glue it together. |

1856, 1857, 1858, 1859