# Tetrahedron

Tetrahedron Facts
Notice these interesting things:
It has 4 Faces
Each face has 3 edges, and is actually an Equilateral Triangle
It has 6 Edges
It has 4 Vertices (corner points)
and at each vertex 3 edges meet

And for reference:
Surface Area = √3 × (Edge Length)2
Volume = (√2)/12 × (Edge Length)3
The plural of tetrahedron is tetrahedra
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.
 The tetrahedron also has a beautiful and unique property ... all four vertices are the same distance from each other! (thanks Ganesh) And it is the only Platonic Solid with no parallel faces.

 When we say "tetrahedron" we often mean "regular tetrahedron" (in other words all faces are the same size and shape) But it could be an irregular tetrahedron, like this one:
 4-Sided Dice? Yes! A tetrahedron that has 4 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 Tetrahedron, cut out the shape and glue it together.