Now you are going to learn how to recognize a polyhedron. You need to know the properties a polyhedron has. A polyhedron is a figure in three dimensions. The figure is composed of polygons.

There are five special polyhedra called the Platonic solids. They are named after one of history’s greatest philosophers, Plato (428 BCE–348 BCE). He discovered that if you put equal regular polygonal faces together, you can create a tetrahedron (four faces), a cube (six faces), an octahedron (eight faces), a dodecahedron (12 faces) or a icosahedron (20 faces). But you can’t create any other polyhedra. This is what these figures look like:

Rule

A polyhedron is a three dimensional figure which is composed of polygons. If you only use one regular polygon type to create a polyhedron, you’ve made a platonic solid.

Platonic solids are composed of one type of polygons. Any three-dimensional figure that is composed of polygons is called a polyhedron. Below, you can see a polyhedron composed of triangles and squares, and a football composed of pentagons and hexagons. So a football is actually a polyhedron!

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Volume and Surface Area of Three-dimensional Figures