1. Regular Polygons:

2. You can tile a floor with triangles squares or hexagons….

3. Angle of a regular k-gon = 108(k-2)/k degrees K=3 gives 60 degrees
But not with pentagons!
Angle of a regular k-gon = 108(k-2)/k degrees
K=3 gives 60 degrees
K=4 gives 90 degrees
K=5 gives 108 degrees, etc….. k
Angle Measure
360/Angle Measure 3 60 6 4 90 5
108
120 7
2.8 8
135 9
140 10
144
2.5

4. Now let’s move to 3 dimensions
Put regular polygons together to form regular polyhedral….
Can we always do this?