# Icosahedron

Icosahedron Facts
Notice these interesting things:
It has 20 Faces
Each face has 3 edges, and is actually an Equilateral Triangle
It has 30 Edges
It has 12 Vertices (corner points)
and at each vertex 5 edges meet

And for reference:
Surface Area = 5×√3 × (Edge Length)2
Volume = 5×(3+√5)/12 × (Edge Length)3
 It is called an icosahedron because it is a polyhedron that has 20 faces (from Greek icosa- meaning 20) If you have more than one icosahedron they are called icosahedra
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 "icosahedron" we often mean "regular icosahedron" (in other words all faces are the same size and shape), but it doesn't have to be - this is also an icosahedron, even though all faces are not the same.
 20-Sided Dice? Yes! An icosahedron that has 20 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 Icosahedron, cut out the shape and glue it together.