That is correct, a polygon must have at least 3 sides. So the simplest polygon is the triangle. There is no upper limit to the number of sides that a polygon can have, although when the number of sides becomes very large, a regular polygon increasingly resembles a circle.
The shape of France is a hexagon, having six sides.
A gigagon is a polygon with a billion sides. To an engineer it would pass as a circle. To a physicist or mathematician it would still be a polygon.
A synonym for France is "l'Hexagone" (the hexagon) because of the rough hexagonal shape (six sides polygon) of the country on a map. It is a very common term, together with "la France métropolitaine", when you need to refer to the territory of metropolitan France without the overseas departments and territories (DOM-TOM).
it seems to me that the only polygon of your description is a square
A type of polygon is a rhombusial polygon, trysectalnict polygon, and a equilateral polygon.
A triangle (not traingle) is a polygon. It can be a regular polygon but need not be.
an arrow is or isn't a polygon?
Polygon B is an octagon.
The definition of a irregular polygon is any polygon that is not a regular polygon.
An equilateral polygon is a polygon where the length of all the sides of the polygon are the same length.
Regular polygon Equilateral polygon Polygon with rotational symmetry