Polygons and PolyhedraPolyhedra
Up to now we have just looked at what we can do with polygons in a flat, two-dimensional world. A A polyhedron (the plural is polyhedra) is a three-dimensional solid with no curved surfaces or edges. All faces of a polyhedron are polygons. For example, a cube and a pyramid are polyhedra, but a sphere is not.
Polyhedra cannot contain curved surfaces – spheres and cylinders, for example, are not polyhedra.
The polygons that make up a polyhedron are called its The faces of a polyhedron are the polygons which make up its surface. The edges of a polyhedron are the line segments where two of its faces are connected. The “corners” of a polyhedron are called its vertices.