Here mine dog "Flame" has actually her challenge made perfect symmetrical v a bitof picture magic.

The white line under the center is present of Symmetry


When the folded part sits perfectly on peak (all edges matching), then the fold line is a line of Symmetry.


Here I have folded a rectangle one way, and also it didn"t work.

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So this is not a heat of Symmetry

But once I try it this way, it does work (the folded part sits perfectly on top, every edges matching):

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So this is a heat of Symmetry

Triangles

A Triangle have the right to have 3, or 1 or no present of symmetry:

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Equilateral Triangle(all political parties equal, all angle equal) Isosceles Triangle(two political parties equal, 2 angles equal) Scalene Triangle(no sides equal, no angles equal)
3 present of Symmetry1 heat of SymmetryNo present of Symmetry

Quadrilaterals

Different varieties of quadrilateral (a 4-sided airplane 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 lines of SymmetryNo present of Symmetry

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KiteRhombus(all sides same length)
1 line of Symmetry2 present of Symmetry

Regular Polygons

A continual polygon has all political parties equal, and all angles equal:

An Equilateral Triangle (3 sides) has 3 present of Symmetry
A Square (4 sides) has 4 lines of Symmetry
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A Regular Pentagon (5 sides) has 5 currently 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 currently of Symmetry
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A Regular Octagon (8 sides) has 8 currently of Symmetry

And the pattern continues:

A regular polygon of 9 sides has actually 9 lines of SymmetryA continual polygon the 10 sides has actually 10 lines of Symmetry...A consistent polygon that "n" sides has "n" currently of Symmetry

Circle