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.

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So this is not a heat of Symmetry

But as soon as I try it this way, it does work (the folded component sits perfect on top, every edges matching):

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So this is a line of Symmetry

Triangles

A Triangle deserve to have 3, or 1 or no currently of symmetry:

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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 Symmetry1 heat of SymmetryNo lines of Symmetry

Quadrilaterals

Different varieties of quadrilateral (a 4-sided aircraft shape):

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Square(all sides equal, all angles 90°) Rectangle(opposite political parties equal, all angle 90°)Irregular Quadrilateral
4 lines of Symmetry2 present of SymmetryNo lines of Symmetry

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KiteRhombus(all sides equal length)
1 heat of Symmetry2 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
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A Regular Pentagon (5 sides) has 5 present of Symmetry
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A Regular Hexagon (6 sides) has 6 currently of Symmetry
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A Regular Heptagon (7 sides) has 7 lines of Symmetry
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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 Symmetry

Circle