### Let's Think About It

Monica pulls into a parking lot and sees a blue sign. She quickly recognizes the sign as a polygon, but she can't remember the exact name of the polygon. She stares at the sign for a few seconds then asks her younger sister to identify the shape. What type of polygon should her younger sister use to describe the sign?

In this concept, you will learn to classify polygons.

### Guidance

A **polygon** is a simple closed figure formed by three or more segments. A triangle is a polygon and a quadrilateral is a polygon, too. Here are three pictures of polygons.

There are several different types of polygons.

Here is a list of the first eight types of polygons.

1. A **triangle** has three sides.

2. A **quadrilateral** has four sides.

3. A **pentagon** has five sides.

4. A **hexagon** has six sides.

5. A **heptagon** has seven sides

6. An **octagon** has eight sides.

7. A **nonagon** has nine sides.

8. A **decagon** has ten sides.

### Guided Practice

Classify the polygon that is represented in the picture.

First, count the number of sides for the television. Do not count the stand.

4

Then, classify the polygon.

Quadrilateral

The answer is that the television is shaped like a quadrilateral.

### Examples

Classify the polygon that is represented in each picture.

#### Example 1

First, count the number of sides.

8

Then, classify the polygon.

Octagon

The answer is that a Stop sign is shaped like an octagon.

#### Example 2

First, count the number of sides.

5

Then, classify the polygon.

5

The answer is that the Pentagon is shaped like a pentagon.

#### Example 3

First, count the number of sides for one of the shapes.

6

Then, classify the polygon.

Hexagon

The answer is a hexagon.

### Follow Up

Remember Monica and the parking sign? She knows that the sign is a polygon, but she can't remember the name. She asks her younger sister. What type of polygon should her younger sister use to describe the shape of the sign?

First, count the number of sides.

4

Then, classify the polygon.

Quadrilateral

The answer is a quadrilateral. Her younger sister should describe the shape of the sign as a quadrilateral

### Video Review

### Explore More

Determine whether or not each image is a polygon. If yes, write polygon, if no, write not a polygon.

1.

2.

3.

4.

5.

6.

7.

8. A square tile on a floor

For numbers 9 – 15, go back and use each figure in 1 – 7. Explain why it is or why it is not a polygon.

9.

10.

11.

12.

13.

14.

15.

### Answers for Explore More Problems

To view the Explore More answers, open this PDF file and look for section 9.12.