Thursday, October 13
Review and finish counting activity of polyhedra.
Do some systematic counting
Discuss connection of face - vertex.
cube inside octa inside cube ...
icoso inside dodeca inside icoso....
tetra inside tetra inside tetra ...
Notice double counting products = 2*number of edges.
[maybe V + F = E + 2?]
in the plane
compared to those
A continuation of the use of analogy.
Rotations: Center point - central axis
Reflection : across line - across plane
Symmetries of the octahedron ( Do for the class) -
determined by opposite vertices. 3
determined by midpoints of opposite sides. 6
determined by midpoints of opposite equilateral triangle faces: 4
across planes mid way between
: 3 (equators)
across planes midway between
symmetries of the cube (Activity):