Here mine dog "Flame" has her face made perfectly symmetrical through a bitof picture magic.
The white line down the facility is theline of Symmetry
When the folded part sits perfect on peak (all edge matching), then the wrinkles line is a line of Symmetry.
Here I have folded a rectangle one way, and it didn"t work.
But once I try it this way, the does work (the folded component sits perfect on top, every edges matching):
Triangles
A Triangle have the right to have 3, or 1 or no present of symmetry:
 |  | |||
| Equilateral Triangle(all sides equal, all angle equal) | Isosceles Triangle(two sides equal, 2 angles equal) | Scalene Triangle(no political parties equal, no angle equal) | ||
| 3 currently of Symmetry | 1 line of Symmetry | No currently of Symmetry |
Quadrilaterals
Different species of quadrilateral (a 4-sided aircraft shape):
 |  | |||
| Square(all sides equal, all angles 90°) | Rectangle(opposite sides equal, all angles 90°) | Irregular Quadrilateral | ||
| 4 present of Symmetry | 2 lines of Symmetry | No lines of Symmetry |
 |  | |
| Kite | Rhombus(all sides same length) | |
| 1 line of Symmetry | 2 lines of Symmetry |
Regular Polygons
A continuous polygon has actually all political parties equal, and all angles equal:
| An Equilateral Triangle (3 sides) has 3 lines of Symmetry | ||
| A Square (4 sides) has 4 present of Symmetry | ||
 | A Regular Pentagon (5 sides) has 5 lines of Symmetry | |
 | A Regular Hexagon (6 sides) has 6 lines of Symmetry | |
 | A Regular Heptagon (7 sides) has 7 present of Symmetry | |
 | A Regular Octagon (8 sides) has 8 currently of Symmetry |
And the pattern continues:
A consistent polygon the 9 sides has 9 lines of SymmetryA consistent polygon that 10 sides has 10 lines of Symmetry...A constant polygon that "n" sides has "n" present of SymmetryCircle |