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# Perimeter review

Review the basics of perimeter and try some practice problems.

## What is perimeter?

Perimeter is the distance around the outside of a two-dimensional shape.
The perimeter of the shapes below is shown in $\text{blue}$.

## How do we calculate the perimeter of a shape?

To find the perimeter of a shape, we add all of the shape's side lengths.

### Example 1:

What is the perimeter of the trapezoid?
We can find the perimeter by adding all of the side lengths.
$\text{Perimeter}=18+8+10+10$

### Example 2:

What is the perimeter of the regular pentagon?
We can find the perimeter by adding all of the side lengths.
All sides of a regular pentagon are the same length.
$\text{Perimeter}=9+9+9+9+9$

## Practice set 1: Calculate perimeter

Problem 1A
What is the perimeter of the triangle?
centimeters

Want to try more problems like this? Check out these exercises:
Find perimeter when given side lengths
Find perimeter by counting unit squares

## Practice set 2: Challenge items

Problem 2A
The perimeter of the figure is .
What is the length of the missing side?
$\text{cm}$

Want to try more problems like this? Check out these exercises:
Find a missing side length when given perimeter
Perimeter word problems

## Want to join the conversation?

• If two or more sides of a shape is unknown, what can you do to figure that out?
• If you want to figure it you have to see the othr stuff first then you would figure it out but if not i don't know it worked for me
• How will I use this in real life?
• So you will use it if you are going to build a house it will also help with fences!
• i like math
• Same
• what is 100x10,000000?
• A certain number.
• its a bit challenging though. you really need analyzing skills for it ahaha.
• I love this so fun it is so fantastic
• Why do you put this here why why!