Let’s Learn!
Can you find the missing side length?
Goal:
Goal:
Think About It!
Goal: Finding the missing side length of a rectangle using \({\Large\text{A} = l \times w}\).
You have learned how to measure the area of a rectangle. Click on the tabs to review each of the ways you can find area.
Tile It
You can count the number of square units.
A grid: 2 rows, 3 columns. Each unit is numbered
1,2,3,4,5,6. There are 6 total square units.
Repeated Addition
You can use repeated addition by adding the number of tiles in each row by the number of rows.
A grid: 2 rows, 3 columns. The rows are labelled number
of rows or groups. The columns are labelled number in
each group. \({3 + 3 = 6}\) square units.
Multiplication
You can also find the area by using \({\Large\text{A} = l \times w}\). This is the way you can identify the measurement of a missing side length of a rectangle.
A rectangle width of 2 units, length 3 units. Area
\({=}\) 3 units \({\times}\) 2 units \({=}\) 6 square
units.
Do you like to solve puzzles? When solving puzzles, you first have to look for clues and use what you know to solve the puzzle. Let's look at how you would find the length of a missing side of a rectangle. Click on each row to reveal the strategy.
A rectangle. width 2 feet. Area equals 10 square
feet.
First, let's look for clues. What information can we gather?
We can see that the measurement of the length is missing. However, we know that the width is 2 ft. and the area is 10 sq. ft.
We can fill in what we know using area equals the length multiplied by the width or \({\Large\text{A}= l \times w}\).
\({\Large10\;\text{sq. ft.}= l \times 2\;\text{ft.}}\)
One way to find the length is to think "What times 2 equals 10?"
You can also use division.
\({\Large10\;\text{sq. ft.} \div 2\;\text{ft.} = 5\;\text{ft.}}\)
The missing length is 5 ft.
You can check your work by substituting the answer from the division problem into the multiplication problem.
\({\Large5\;\text{ft.} \times 2\;\text{ft.}= 10\;\text{sq. ft.} }\)