A. A polyhedron is a 3-dimensional multi-faced figure with uniform sides of identical shapes.
B. The most common polyhedrons are:
1. Tetrahedron - A tetrahedron has 4 faces all of which are triangles.
2. Octahedron - An octahedron has 8 faces all of which are triangles.
3. Decahedron - A decahedron has 10 faces all of which are pentagons.
4. Dodecahedron - A dodecahedron has 12 faces all of which are pentagons.
5. Icosahedron - An icosahedron has 20 faces all of which are triangles.
C. Examples
Ex [1] An dodecahedron has how many faces? ______
a. The answer is 12.
Ex [2] Each face of a decahedron has how many sides? ____
a. Since each face is a pentagon, each face has 5 sides.