Polygons

Classification of Polygons on the Basis of their Sides

Look at the following figures.

What do we observe in these figures?

We observe that each figure is made up of line segments only and has different number of sides. All these figures are known as polygons. We know that polygons with three sides are known as triangles and polygons with 4 sides are known as quadrilaterals.

But how do we classify the polygons having more than four sides?

Let us see.

We can classify polygons on the basis of the number of sides as follows:

• Pentagon: Polygon having five sides

• Hexagon: Polygon having six sides

• Heptagon: Polygon having seven sides

• Octagon: Polygon having eight sides

• Nonagon: Polygon having nine sides

• Decagon: Polygon having ten sides

Therefore, now we can classify the polygons in the above given figures.

Let us now look at some more examples to understand this concept better.

Example 1:

Identify and name the polygons out of the following figures.

Solution:

1. The closed figure is made of nine line segments. Therefore, it is a nonagon.
2. The closed figure has a curve. Therefore, it is not a polygon.
3. The closed figure has a curve. Therefore, it is not a polygon.
4. The figure has only one line segment. A polygon should have at least three line segments. Therefore, it is not a polygon.
5. The closed figure is made of six line segments. Therefore, it is a hexagon.
6. The closed figure is made of five line segments. Therefore, it is a pentagon.
7. The closed figure is a curve. Therefore, it is not a polygon.
8. The closed figure is made of nine line segments. Therefore, it is a nonagon.
9. The figure is not closed. Therefore, it cannot be a polygon.
10. The closed figure has curves. Therefore, it is not a polygon.

Example 2:

Name the following polygons.

Solution: