What Are Polygons?

      A polygon is a closed, two-dimensional shape that has straight sides.

Look at these shapes.

Only shape 1 is a polygon.

The 3 Features of Polygons

      A polygon is a closed shape. It has no openings. This means it has line segments that start and end at the same point. 

      A polygon is two-dimensional, or 2D, which means it's flat. It has no depth, only length and width.

      A polygon has straight sides. It has no curved sides.

Examples of Polygons

Some examples of polygons are shown below.

Most 2D shapes are polygons.

A circle isn't a polygon. That's because it has no straight lines.

Identifying Polygons

Let's see if you can identify, or recognize, polygons below.

Which of these shapes are polygons?

Tip: To know if a shape is a polygon, check if it's flat, closed, and has straight sides.

Let's check each shape for the 3 features.

So, which of these shapes are polygons?

Very good! Shapes 2 and 6 are polygons.

Great work. 👏

Names of Polygons

Polygons have special names based on their sides and vertices.

For example,

      3-sided polygons are called triangles.

      4-sided polygons are called quadrilaterals.

      5-sided polygons are called pentagons.

      6-sided polygons are called hexagons.

      7-sided polygons are called heptagons.

      8-sided polygons are called octagons.

Great job learning about polygons.

Now, try the practice to help you remember what polygons are.