2D Shapes

Regular Polygons

A polygon is a plane (2D) shape with straight sides.
To be a regular polygon all the sides and angles must be the same:

Triangle - 3 Sides	Square - 4 Sides
Pentagon - 5 Sides	Hexagon - 6 sides
Heptagon - 7 Sides	Octagon - 8 Sides
Nonagon - 9 Sides	Decagon - 10 Sides
More ...

Other Common Polygons

Quadrilateral Any 4 sided 2D shape	Rectangle - 4 Sides All right angles
And many more!

Curved Shapes

These 2D shapes have curves, so are not polygons:

Circle

Ellipse