1. Three-Dimensional Figures
Math Alliance
March 21, 2011

2. Polyhedrons In your group, define the following terms: Face: Edge:
Vertex:
Polyhedron: “poly” – many, “hedron” – side/base
Grab Bag Activity
any of the polygons that make up its boundaries
The set of points where two faces intersect.
A point where 3 or more edges meet.

3. Polyhedrons?
Are the following Polyhedrons?

4. Euler’s Formula
Using the shapes in your crate, complete the following table:
Polyhedron
# of Vertices
# of Faces
Faces + Vertices
Edges

5. Euler’s Formula
What happens to Euler’s formula when you truncate (cut a corner off) a polyhedron?
Explain your reasoning.

7. Regular Polyhedrons
How would you define a regular polyhedron? (Turn and talk.)
Using the straws and pipe cleaners, which different regular polyhedrons can you create?

8. Regular Polyhedrons There are exactly 5 regular polyhedra:
How do we know we have found them all?
Tetrahedron
Hexahedron
Octahedron
Icosahedron
Dodecahedron

9. Homework
Section 11.4
#’s - 7, 8, 9, 10, 11, 12, 15, 21, 22, 37, 40, 44, 51
Turn in: 7, 12, 15, 22, 37, 51

10. Cylinders, Spheres, & Cones