Three-Dimensional Figures, or Solids

Polyhedra

A polyhedron is a three-dimensional solid, each face of which is a polygon. Each pair of faces meet at an edge. The corners of the edges meet at points called vertices.

	A prism is a polyhedron that has two parallel, congruent faces called bases. The other faces are parallelograms. This rectangular prism has six faces, twelve edges, and eight vertices.
	A cube is a prism whose faces are squares. This cube has six faces, twelve edges, and eight vertices.
	A pyramid is a polyhedron whose base is a polygon and whose faces are triangles with a common vertex. This triangular pyramid has four faces, six edges, and four vertices. This square pyramid has five faces, eight edges, and five vertices.

Other 3-D Figures

These are solids that are not formed by polygons.

	A cylinder is a solid whose bases are circles.
	A cone is a solid with one circular base and one vertex
	A sphere is the set of all points in space that are equidistant from a given point called the center.

Review

• A polyhedron is a three-dimensional solid where each face is a polygon. Some examples are:
  • prisms
  • cubes
  • pyramids
• Other three-dimensional figures (not formed by polygons) include:
  • cylinders
  • cones
  • spheres