1. Learn to identify various three-dimensional figures.

2. Vocabulary prism face pyramid edge polyhedron cylinder vertex cone
sphere
face
edge
polyhedron
vertex
base

3. Three-dimensional figures have three dimensions: length, width, and height. A flat surface of a three-dimensional figure is a face. An edge is where two faces meet. A vertex is a point where three or more edges meet.

4. A polyhedron is a three-dimensional figure whose faces are all polygons. The face that is used to name a polyhedron is a base.

5. Additional Example 1A: Naming Prisms and Pyramids
Identify the bases and faces of the figure. Then name the figure.
There are two octagonal bases.
There are eight rectangular faces.
The figure is an octagonal prism.

6. Additional Example 1B: Naming Prisms and Pyramids
Identify the bases and faces of the figure. Then name the figure.
There is one base, and it is a pentagon.
There are five triangular faces.
The figure is a pentagonal pyramid.

7. Additional Example 1C: Naming Prisms and Pyramids
Identify the bases and faces of the figure. Then name the figure.
There is one base, and it is a triangle.
There are three triangular faces.
The figure is a triangular pyramid.

8. Additional Example 1D: Naming Prisms and Pyramids
Identify the bases and faces of the figure. Then name the figure.
There are two bases, and they are both hexagons.
There are six rectangular faces.
The figure is a hexagonal prism.

9. Check It Out: Example 1A
Identify the bases and faces of the figure. Then name the figure.
There are two bases and they are both triangles.
There are three rectangular faces.
The figure is a triangular prism.

10. Check It Out: Example 1B
Identify the bases and faces of the figure. Then name the figure.
All faces and bases are congruent squares.
The figure is a cube.

11. Other three-dimensional figures include cylinders, cones, and spheres
Other three-dimensional figures include cylinders, cones, and spheres. These figures are not polyhedrons because they are not made of faces that are all polygons.

12. You can use properties to classify three- dimensional figures.

13. Additional Example 2A: Classifying Three- Dimensional Figures
Classify each figure as a polyhedron or not a polyhedron. Then name the figure.
The faces are all polygons, so the figure is a polyhedron.
There is one rectangular base for each figure.
The figure is made up of a rectangular pyramid and a rectangular prism.

14. Additional Example 2B: Classifying Three- Dimensional Figures
Classify each figure as a polyhedron or not a polyhedron. Then name the figure.
The faces are not all polygons, so the figure is not a polyhedron.
There is one circular base.
The figure is a cone.

15. Additional Example 2C: Classifying Three- Dimensional Figures
Classify each figure as a polyhedron or not a polyhedron. Then name the figure.
The faces are not all polygons, so the figure is not a polyhedron.
There are two circular bases.
The figure is a cylinder.

16. Check It Out: Example 2A
Classify each figure as a polyhedron or not a polyhedron. Then name the figure.
The faces are not all polygons, so the figure is not a polyhedron.
There is one circular base for the top figure and two circular bases for the bottom figure.
The figure is made up of a cylinder and a cone.

17. Check It Out: Example 2B
Classify each figure as a polyhedron or not a polyhedron. Then name the figure.
The faces are all polygons, so the figure is a polyhedron.
There are two triangular bases for the figure.
The figure is a triangular prism.

18. Check It Out: Example 2C
Classify each figure as a polyhedron or not a polyhedron. Then name the figure.
The faces are all polygons, so the figure is a polyhedron.
There is one square base for the figure.
The figure is a square pyramid.