February 10

Review from last class:

180/360 = 1/n + 1/k + 1/p  or
1/n + 1/k + 1/p=1/2
1/3+1/4+1/5 >1/2.

Why is this called "duality"?
Back and forth in the construction
We place a point in each  region(polygon) .
Every vertex of the old figure is surrounded by a region( polygon) in the new figure.
"Having two forms"...   point.... region

Other dualities?

Symmetry Ideas