- Last time: platonic solids
- Today:
- Hand back homework (3.3 - 7 and 11; 4.1 - 3 and 5)
- I'll be letting you out a little early today -- there's a banquet and special speaker tonight, and I'm a "host" and need to get there at 6:00....
- Collect homework, sections 4.3
- Project issues....
- A little more on the Platonic solids
- Why the symmetry in the table we put together for the
five Platonic Solids (What is this thing called duality?)?
| |
# of Vertices |
Edges |
Faces |
faces at each vertex |
sides at each face |
| Tetrahedron |
4 |
6 |
4 |
3 |
3 |
| Tetrahedron |
4 |
6 |
4 |
3 |
3 |
| Cube |
8 |
12 |
6 |
3 |
4 |
| Octahedron |
6 |
12 |
8 |
4 |
3 |
| Dodecahedron |
20 |
30 |
12 |
3 |
5 |
| Icosahedron |
12 |
30 |
20 |
5 |
3 |
- What is "rubber sheet geometry"? How can we characterize it?
- circle's a square is a triangle is a ....
- The ring
- The button problem (#8, p. 339) (from your kit)
- The handcuffs (problem #12, p. 340)
- Next time: The band that won't
stop playing (Section 5.2)
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