In: Advanced Math
Write the multiplication table for D8. Find the order of each element D8.
Here, denotes the identity element, is an element of order 4, and is an element of order two that isn't equal to , as in the above presentation.
The row element is multiplied on the left and the column element is multiplied on the right.
Element | ||||||||
---|---|---|---|---|---|---|---|---|
Ordee of each element:
Element in terms of and | Geometric description | Permutation on vertices | Order of the element |
---|---|---|---|
(identity element) | does nothing, i.e., leaves the square invariant | 1 | |
rotation by angle of (i.e., ) counterclockwise | 4 | ||
rotation by angle of (i.e., ), also called a half turn | 2 | ||
rotation by angle of (i.e., ) counter-clockwise, or equivalently, by (i.e., ) clockwise | 4 | ||
reflection about the diagonal joining vertices "2" and "4" | 2 | ||
reflection about the line joining midpoints of opposite sides "14" and "23" | 2 | ||
reflection about the diagonal joining vertices "1" and "3" | 2 | ||
reflection about the line joining midpoints of opposite sides "12" and "34" | 2 |