# Classification of polygons

## Polygons – **Classification**

We classify polygons to the number of side or

vertices based they have.

A polygon can be classified by it’s number of a sides and measure of angles.

First, we classify by it’s number of a sides.

**Classified by measuring the sides**

The name of a polygon usually depends on how many sides or lines the shape has.

Any shape that can be drawn by three connecting straight lines is a triangle, shape that can be drawn by four connecting straight lines is a quadrilateral, and shape that can be drawn by five connecting straight lines is a pentagon.

if a polygon has three sides it’s called triangle, if it has four sides it’s called quadrilateral,if it has five sides it’s called pentagon.

**Note:** A circle is not a polygon because it is formed with curved line, if any curved line is used to form a close figure than it will not be a polygon.

There are some names of polygons that usually occur in everyday.

**Sides Polygon **

**3 Triangle **

** 4 quadrilateral **

**5 pentagon**

**6 hexagon**

**7 heptagon**

**8 octagon**

**9 nonagon**

**10 decagon**

**12 dodecagon**

**n sides n-gon**

When a polygon has 300 sides it will be known as 300-gon.

**Triangle:** A three sided polygon is known as the triangle.

**Quadrilateral:** A four sided polygon is known as the quadrilateral.

**Pentagon:** The five sided polygon is known as the pentagon.

**Hexagon: **The closed figure which is formed by six straight lines is known as hexagon.

**Heptagon:** A polygon which has seven sides is known as heptagon.

**Octagon: **A closed figure which is made by eight straight lines is known as octagon.

**Nonagon:** As the name says, the nine sided polygon is known as nonagon.

**Decagon:** The closed figure which is formed by ten straight lines is known as decagon.

**1. Triangle:**

a. Number of sides or vertices = 3

b. Figure

**2. Quadrilateral:**

a. Number of sides or vertices = 4

b. Figure

**3. Pentagon:**

a. Number of sides or vertices = 5

b. Figure

**4. Hexagon:**

a. Number of sides or vertices = 6

b. Figure

**5. Heptagon:**

a. Number of sides or vertices = 7

b. Figure

**6. Octagon:**

a. Number of sides or vertices = 8

b. Figure

**7. Decagon:**

a. Number of sides or vertices = 10

b. Figure

**8. Dodecagon:**

a. Number of sides or vertices = 12

b. Figure

Classified by measuring the angles

** Regular polygon**

A polygon which has all sides are congruent(equal) and all angles are congruent (equal) is known as a regular polygon.

If a triangle has all the sides are same and all the angles are same then it is a equilateral triangle or a regular triangle.

If a quadrilateral has all the sides are same and all the angles are same then it is a square or a regular quadrilateral..

**Irregular polygon**A polygon which has all sides are not congruent(not equal) or different in length and all angles are not congruent (not equal) or different in measure the polygon is known as a irregular polygon.

Above all of shapes are polygons. We notice that all the shapes are drawn with only straight lines and all the sides are connect. ** Not a polygon**

In above shapes we notice that one shape is curved and other shape all the straight lines are not fully connected, so it can’t be called a polygon.