Warm Up Identify each two-dimensional figure described. 1. four sides that are all congruent 2. six sides 3. four sides with parallel opposite sides 4. four right angles and four congruent sides rhombus hexagon parallelogram square

Learn to identify various three-dimensional figures.

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

Three-dimensional figures have three dimensions: length, width, and height. A flat surface of a three-dimensional figure is a face. A polyhedron is a three-dimensional figure whose faces are all polygons. A vertex of a polyhedron is a point where three or more edges meet. The face that is used to name a polyhedron is a base. A prism has two bases, and a pyramid has one.

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.

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.

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.

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.

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.

You can use properties to classify three- dimensional figures.

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.

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.

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.

Lesson Quiz for Student Response Systems 1. Identify the bases and faces, and then the name of the given figure. A. pentagon; triangles; pentagonal prism B. hexagon; triangles; hexagonal prism C. pentagon; triangles; pentagonal pyramid D. hexagon; triangles; hexagonal pyramid 15 15

Lesson Quiz for Student Response Systems 2. Identify the bases and faces, and then the name of the given figure. A. pentagon; triangles; pentagonal pyramid B. heptagon; triangles; heptagonal pyramid C. pentagon; rectangles; pentagonal prism D. heptagon; rectangles; heptagonal prism 16 16

Lesson Quiz for Student Response Systems 3. Classify the figure as a polyhedron or not a polyhedron, and then name the given figure. A. polyhedron; pentagonal prism B. polyhedron; pentagonal pyramid C. not a polyhedron; cylinder D. not a polyhedron; cone 17 17

Lesson Quiz for Student Response Systems 4. Classify the figure as a polyhedron or not a polyhedron, and then name the given figure. A. polyhedron; heptagonal prism B. polyhedron; nonagonal pyramid C. not a polyhedron; cylinder D. not a polyhedron; cone 18 18