Three-Dimensional Figures Math Alliance March 21, 2011

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.

Polyhedrons? Are the following Polyhedrons?

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

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

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?

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

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

Cylinders, Spheres, & Cones