### Theory:

What do you think makes an army marching past visually-pleasing?

If we observe the Republic day parade on television, we might find the army people marching past synchronously. A lot of practice and discipline has gone into it.

The army people, in the same uniform, move together like a one-piece. This uniformity makes this activity pleasing to the eyes.

If you observe, the army people are equally-spaced and exhibit oneness. This synchronization in space, look, and motion is called symmetry.

Symmetry is all around the world. Symmetry associates itself with geometry, nature and human-made things. It is there in the leaves of a book, in the long-grown grass, and the newly constructed building.

Symmetry:
An object is said to be symmetrical when it can be cut into two identical halves.

The line that cuts the object into two identical halves is called the line of symmetry or the axis of symmetry.

The line of symmetry can either be vertical, horizontal or diagonal.

Some objects can be cut into two or more identical halves. In other words, there can be more than one line of symmetry.

Figures with one line of symmetry:

Figures with two lines of symmetry:

Figures with more than two lines of symmetry:

These type of figures are all regular polygons where all the sides are equal.

In a regular polygon, the number of sides equals the number of lines of symmetry.

The number of sides $$=$$ The number of lines of symmetry