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.

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So this is not a heat of Symmetry

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

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So this is a heat of Symmetry

Triangles

A Triangle can have 3, or 1 or no lines of symmetry:

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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 Symmetry1 heat of SymmetryNo currently of Symmetry

Quadrilaterals

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

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Square(all sides equal, all angle 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 heat of Symmetry2 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
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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 present of Symmetry
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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 Symmetry

Circle