# Finding Perimeter with Given Side Lengths

Rating

Ø 4.3 / 3 ratings
The authors
Team Digital
Finding Perimeter with Given Side Lengths
CCSS.MATH.CONTENT.3.MD.D.8

## Finding Perimeter with Given Side Lengths

It is summer time and in order to make summer evenings even better, your family wants to decorate the space around your pool with string lights. However, you will need to determine the perimeter of the pool in order to buy enough lights to string around the edges. This 3rd grade video and text teaches you how to find the perimeter of a shape with given side lengths. Continue reading if you want to learn how to solve for perimeter.

## What Is Perimeter?

### Perimeter – Definition

The perimeter means the total distance around a figure, or the sum of all its sides. Finding the perimeter of any shape, regular or irregular, is simple: add up the lengths of each side to calculate the perimeter. The perimeter is always labeled using the correct unit of measure. Common units for perimeter might be centimeters, inches, feet, yards, meters, miles, and kilometers.

### Perimeter vs. Circumference

Circumference is a special name given to a circle’s perimeter. However, finding the circumference requires a special perimeter formula. It is not just adding side lengths.

## Finding Perimeter

The perimeter equals the sum of all a figure's side lengths. When finding a perimeter, begin by looking at the shape’s side measurements. For our pool, the sides are labeled fourteen feet, six feet, fourteen feet and six feet:

Next, write the equation for perimeter by adding all the side lengths together: 14+ 6 + 14 + 6:

Then, determine the perimeter by calculating the sum and labeling with correct units. The solution to this perimeter problem is 40 feet. This means, we need to buy 40 feet of string lights for the pool area.

## How to Find the Perimeter of Polygons – Formulas and Examples

In the table below are several examples of polygon perimeters.

Polygon Perimeter
triangle side 1 + side 2 + side 3

square, rectangle, parallelogram, trapezoid, rhombus
side 1 + side 2 + side 3 + side 4
pentagon side 1 + side 2 + side 3 + side 4 + side 5
hexagon side 1 + side 2 + side 3 + side 4 + side 5 + side 6
octagon side 1 + side 2 + side 3 + side 4+ side 5 + side 6 + side 7 + side 8

For a better visual illustration, the following infographics show the perimeters of a pentagon, a hexagon and an octagon:

## How to Get the Perimeter – Summary of Steps

• First, look at the figure's side measurements.

• Next, write the equation for perimeter by adding all the side lengths together.

• Then, determine the perimeter by calculating the sum.

• Finally, label the answer with correct units.

Have you practiced perimeter problems yet? On this website, you can also find 3rd grade perimeter worksheets and exercises.

### TranscriptFinding Perimeter with Given Side Lengths

1 comment
1 comment
1. cool

From Isabella, 6 months ago

## Finding Perimeter with Given Side Lengths exercise

Would you like to apply the knowledge you’ve learned? You can review and practice it with the tasks for the video Finding Perimeter with Given Side Lengths.
• ### What is the perimeter of the yard?

Hints

Remember, the perimeter is the distance around the shape. It is the total length of all the shape's sides.

As an example, this is how you would find the perimeter for the rectangle below.

Solution

The perimeter of a shape is the distance around the shape.
To find the perimeter, we must find the sum of the shape's sides by adding.

10 + 15 + 10 + 15 = 50
The perimeter of the yard is 50 yards.

• ### How do you find the perimeter of a shape?

Hints

Looking at the picture of the rectangle, what is the first step to find the perimeter?

To find the perimeter, you must add the length of all sides of the shape.

Remember - it is important to include the measurement units!

Solution

Perimeter is the distance around an object. To find the perimeter you must:

1. Identify the side lengths and units of the figure.
3. Add by calculating the sum of the sides.
4. Rewrite the sum with the correct units next to the perimeter.
• ### What is the perimeter of each shape?

Hints

The perimeter of a shape is the distance around the shape. It is the total length of the shape's sides. To find the perimeter, find the total length of the shape's sides.

As an example, this is how you would find the perimeter for the shape below.

Solution

Perimeter is the distance around a shape. To find the perimeter, find the total length of the shape's sides.

Rectangle: 7 + 20 + 7 + 20 = 54
The perimeter of the rectangle is 54 inches.

Triangle: 15 + 15 + 15 = 45
The perimeter of the triangle is 45 inches.

Square: 12 + 12 + 12 + 12 = 48
The perimeter of the square is 48 inches.

Rhombus: 13 + 13 + 13 + 13 = 52
The perimeter of the rhombus is 52 inches.

• ### What is the perimeter of each window?

Hints

The perimeter of a shape is the distance around the shape.

Add the lengths of the sides to find the total distance around the shape.

As an example, this is how you would find the perimeter for the shape below.

Solution

The perimeter of a shape is the distance around the shape. To find the perimeter find the total length of the shape's sides.

Window 1:
16 + 12 + 14 + 18 = 60
The perimeter of window 1 is 60 inches.

Window 2:
14 + 28 + 14 + 28 = 84
The perimeter of window 2 is 84 inches.

Window 3:
14 + 22 + 18 + 28 = 82
The perimeter of window 3 is 82 inches.

• ### What is the perimeter of the pentagon?

Hints

The perimeter of a shape is the distance around the shape. It is the total length of the shape's sides.

To calculate the perimeter, you must find the sum of the shape's sides. As an example, this is how you would find the perimeter for the shape below.

Solution

The perimeter of a shape is the distance around the shape. It is the total length of the shape's sides.

To find the perimeter, add the lengths of each side of the pentagon.

3 + 3 + 3 + 3 + 3 = 15

The perimeter of the pentagon is 15 centimeters.

• ### Which shapes have a perimeter of 24 feet?

Hints

More than one shape has a perimeter of 24 feet.

Perimeter is the distance around a shape. As an example, this is how you would find the perimeter for the rectangle below.

Solution

The perimeter of a shape is the distance around the shape. It is the total length of the shape's sides.

To find the perimeter:

1. Identify the side lengths and labels.
2. Add to find the sum, or total length, of the perimeter of the shape.

Square:
6 + 6 + 6 + 6 = 24
The perimeter of the square is 24 feet.

Rectangle:
3 + 9 + 3 + 9 = 24
The perimeter of the rectangle is 24 feet.

Pentagon:
5 + 5 + 5 + 5 + 5 = 25
The perimeter of the pentagon is NOT 24 feet.

Triangle:
8 + 8 + 8 = 24
The perimeter of the triangle is 24 feet.