Here my dog "Flame" has actually her face made perfect symmetrical with a bitof photo magic.
The white line down the facility is present of Symmetry
When the folded component sits perfect on peak (all edges 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 can have 3, or 1 or no lines of symmetry:
 |  | |||
| Equilateral Triangle(all sides equal, all angle equal) | Isosceles Triangle(two political parties equal, two angles equal) | Scalene Triangle(no sides equal, no angle equal) | ||
| 3 present of Symmetry | 1 heat of Symmetry | No currently of Symmetry |
Quadrilaterals
Different types of quadrilateral (a 4-sided aircraft shape):
 |  | |||
| Square(all sides equal, all angle 90°) | Rectangle(opposite political parties equal, all angle 90°) | Irregular Quadrilateral | ||
| 4 lines of Symmetry | 2 lines of Symmetry | No present of Symmetry |
 |  | |
| Kite | Rhombus(all sides same length) | |
| 1 heat of Symmetry | 2 present of Symmetry |
Regular Polygons
A consistent polygon has all sides equal, and all angles equal:
| An Equilateral Triangle (3 sides) has 3 currently of Symmetry | ||
| A Square (4 sides) has 4 lines of Symmetry | ||
 | A Regular Pentagon (5 sides) has 5 present of Symmetry | |
 | A Regular Hexagon (6 sides) has 6 currently of Symmetry | |
 | A Regular Heptagon (7 sides) has 7 present of Symmetry | |
 | A Regular Octagon (8 sides) has 8 lines of Symmetry |
And the pattern continues:
A constant polygon of 9 sides has actually 9 currently of SymmetryA continuous polygon of 10 sides has 10 present of Symmetry...A regular polygon of "n" sides has actually "n" currently of SymmetryCircle |