Theory:

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Symmetry comes from a Greek word meaning 'to measure together'.
 
Symmetry is widespread in nature, where there was no human hand intervention. It can be observed in the form of leaves and flowers of plants, in the arrangement of various animal organs, in the form of crystalline bodies, in a butterfly, a mysterious snowflake, starfish.
 
Artists, professionals, designers of clothing or jewellery, car manufacturers, architects and many others use the idea of symmetry.
If two or more parts of a figure are identical after folding, then it is said to be symmetry. An image is said to be symmetrical when two halves of an image are of same shape and size.
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Line of symmetry:
An imaginary line divides a figure into two equal halves, and the line is called a line of symmetry or axis of symmetry.
 
> Line of symmetry can be horizontal, vertical or diagonal.
> There can be one or more lines of symmetry in a figure
 
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Lines of symmetry for regular polygons:
We know that all the sides and angles of a polygon are equal then it is said to be a regular polygon. Example: equilateral triangle, square etc.
 
All the regular polygons are symmetrical in shapes. In a regular polygon, the number of its sides is equal to the number of lines of symmetry.
 
Shape
Number of sides
Lines of symmetry
Figure
Equilateral triangle
3
3
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Square
4
4
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Pentagon
5
5
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Hexagon
6
6
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