Reflectional symmetry?

The principle of reflectional symmetry is that when you draw a line on the figure, if you find that the pattern on both sides of the line(which is known as the axis of symmetry) is exactly the same, then there is reflectional symmetry. The more lines that you can draw, the more symmetry. For example:
1) An isos. triangle has 1 line of reflectional symmetry.
2) The capital letter G has no line of reflectional symmetry.
3) A circle has infinite number of lines of reflectional symmetry.

2008-07-11 11:57:32 補充：
The axis of symmetry is like a mirror, if the object on one side and the image on the other side is exactly the same, then there is reflectional symmetry.