Here mine dog "Flame" has her face made perfect symmetrical v a bitof photo magic.
The white line under the center is theline of Symmetry
When the folded part sits perfectly on optimal (all edges matching), then the fold line is a heat of Symmetry.
Here I have actually folded a rectangle one way, and also it didn"t work.
But as soon as I try it this way, it does work (the folded component sits perfect on top, every edges matching):
Triangles
A Triangle deserve to have 3, or 1 or no currently of symmetry:
 |  | |||
| Equilateral Triangle(all sides equal, all angles equal) | Isosceles Triangle(two sides equal, 2 angles equal) | Scalene Triangle(no political parties equal, no angles equal) | ||
| 3 currently of Symmetry | 1 heat of Symmetry | No lines of Symmetry |
Quadrilaterals
Different varieties of quadrilateral (a 4-sided aircraft shape):
 |  | |||
| Square(all sides equal, all angles 90°) | Rectangle(opposite political parties equal, all angle 90°) | Irregular Quadrilateral | ||
| 4 lines of Symmetry | 2 present of Symmetry | No lines of Symmetry |
 |  | |
| Kite | Rhombus(all sides equal length) | |
| 1 heat of Symmetry | 2 lines of Symmetry |
Regular Polygons
A constant polygon has actually all political parties equal, and also all angle equal:
| An Equilateral Triangle (3 sides) has 3 currently of Symmetry | ||
| A Square (4 sides) has 4 currently 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 lines of Symmetry | |
 | A Regular Octagon (8 sides) has 8 present of Symmetry |
And the pattern continues:
A constant polygon the 9 sides has 9 currently of SymmetryA constant polygon of 10 sides has 10 lines of Symmetry...A constant polygon the "n" sides has "n" currently of SymmetryCircle |