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## Basic geometry and measurement

### Course: Basic geometry and measurement>Unit 1

Lesson 6: Perimeter intro

# 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?
• why build when you can buy? so much easier
(1 vote)
• Yeah, I agree, Mr. Taylor—I got confused, the angle change puzzled me, but I realized my mistake and corrected it.
• its a bit challenging though. you really need analyzing skills for it ahaha.
• can you calculate this problem please. A piece of wire 80cm long is bent to form a rectangle. Find the dimensions of the rectangle so that its area us as large as possible.
• A square will give most area. Square with four sides of 20cm each. Therefore to find area we multiply length * width: 20 * 20 = 400 cm²
• i like math
• Same