A polygon is a closed figure made up of line segments.
Polygons can be described as flat closed figures with 3 or more sides.
As you can see, not all polygons are regularly shaped. Some of them look quite odd.
These two sides are reflections or mirror images, and is also referred to as reflection symmetry.
In order to be a polygon, a shape must meet two requirements:
Is it a polygon?
Yes, this is a polygon because it is closed and it is made of line segments (no curves.)
Is it a polygon?
No, this is not a polygon because it is not made of line segments. (It has a curve.)