Area of Rectangles

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Area of Rectangles
CCSS.MATH.CONTENT.3.MD.C.7.A

Finding the Area of Squares and Rectangles

How many suitcases fit in the trunk of your parents’ car? To find out, you need to learn about finding the area of rectangles and squares.Finding the area of squares and rectangles is a simple process.

• The formula for finding area is area = length x width.

Finding the Area of Squares and Rectangles – Example

Let’s look at an example of a rectangle and how to find the area of our example rectangle. These are the steps to follow in order to find the area of the rectangle.

• First, you count the unit squares along the length.
• Then you count the unit squares along the width.
• Finally, you multiply the length by the width to find the area.

In the below example, the length is five, and the width is three. We multiply them to get fifteen, which is our area!

Finding the Area of Rectangles and Squares – Steps

These are the steps to follow when you need to find the area of a rectangle or a square:

Step # What to do
1 Count the unit squares along the length.
2 Count the unit squares along the width.
3 Multiply the unit squares length by
width to find the area.

Using our example from earlier, this is how you use the formula to find the area of a square or a rectangle:

Formula: length x width = area
Example: 5 x 3 = 15

Finding the Area of Rectangles and Squares – Summary

Remember, to find the area of rectangles and squares, use the formula area = length x width. Count the length, then count the width, and finally multiply them together to find the area. After watching the video, you will find area of rectangles and squares exercises and worksheets.

TranscriptArea of Rectangles

Zuri and Freddie are getting ready to hunt for some new items for their home. They need help determining the area of some items, so they can decide if they will fit or not. To do this, we will find the area of rectangles. Area is the amount of space taken up by an object on a flat surface. To calculate the area of rectangles we can use a multiplication formula; area equals length times width. First, count the unit squares along the length, replacing length with this number. Next, count the unit squares along the width, replacing width with this number. There are five unit squares in every row and we have three rows, so we need to find five multiplied by three! That means we multiply the length by the width to find the area of the rectangle. Five multiplied by three is fifteen, so this rectangle would be fifteen square units. Let's calculate the area of Zuri and Freddie's home first so they know how much space they have. Here is the floor plan. Remember the formula; area equals length times width. First, count the unit squares along the length, which is six. Now count the unit squares along the width. Multiply six by four, which is twenty-four! Zuri and Freddie's home is twenty-four square units. It looks like Freddie has found a rug, so let's help find the area! Remember; area equals length times width. What is the first step? Count the unit squares along the length. How many unit squares is the length? It is seven. What is the next step? Count the unit squares along with the width. How many unit squares wide is the rug? It is four unit squares wide. Now calculate the area. What is seven times four? It is twenty-eight, so the rug has an area of twenty-eight square units! "Hmm, that's probably not going to fit because our home is only twenty-four square units. How about this?" Zuri found a coffee table, so let's calculate the area! The formula for calculating area still works here because a square is also a rectangle! Use the formula, area equals length times width. What is the multiplication sentence for the area of the coffee table? It is two times two. What is two times two? It is four, so the area of the coffee table is four square units! "That will fit perfectly, Zuri!" While Zuri and Freddie finish up, let's review. Remember, to calculate the area of rectangles you can use area equals length times width. First, count the unit squares along the length. Next, count the unit squares along the width. Finally, multiply the length by the width to find the area. "Freddie, what are you doing?" "The rug may not fit our home, but it sure makes a great royal cape to be king for a day!"

Area of Rectangles exercise

Would you like to apply the knowledge you’ve learned? You can review and practice it with the tasks for the video Area of Rectangles .
• How do you find the area of a rectangle?

Hints

First of all, we need to find the length and the width of the rectangle.

Once we know the length and width measurements, we can multiply them together to find the answer.

Solution
• First, count the unit squares along the length, for example, in the picture above the length is 4 units.
• Next, count the unit squares along the width, for example, in the picture above the width is 3 units.
• Multiply the length by the width, for example, 4 x 3.
• Solve the multiplication equation, for example, 4 x 3 = 12. We now know the area of the rectangle: 12 square units.
• Calculate the area of each item.

Hints

Figure out the length and the width of each item first.

Multiply the length by the width to find out the area.

Solution

This is the area of each rectangular item.

18 square units

• The length is 6 units.
• The width is 3 units.
• 6 x 3 = 18
• The area is 18 square units.
24 square units
• The length is 4 units.
• The width is 6 units.
• 4 x 6 = 24
• The area is 24 square units.
60 square units
• The length is 10 units.
• The width is 6 units.
• 10 x 6 = 60
• The area is 60 square units.
55 square units
• The length is 11 units.
• The width is 5 units.
• 11 x 5 = 55
• The area is 55 square units.

• What is the area of each object?

Hints

Remember, to figure out the area we need to multiply the length by the width.

For example, to find the area of this rectangle we would multiply 7 x 2.

Solution

Here is the area of each rectangular object.

6 square units

• The length of this rectangle is 3 units.
• The width of this rectangle is 2 units.
• 3 x 2 = 6
• The area is 6 square units
10 square units

• The length of this rectangle is 5 units.
• The width of this rectangle is 2 units.
• 5 x 2 = 10
• The area is 10 square units
15 square units

• The length of this rectangle is 5 units.
• The width of this rectangle is 3 units.
• 5 x 3 = 15
• The area is 15 square units
8 square units

• The length of this rectangle is 4 units.
• The width of this rectangle is 2 units.
• 4 x 2 = 8
• The area is 8 square units
• What is the area?

Hints

figure out the area of each rectangle by multiplying the length by the width.

Do you know the factors of 12 and 24? These could help you to sort the areas.

Solution

Here are the rectangles correctly highlighted.

24 square units (blue)

• Four rectangles had an area of 24 square units:
• 3 x 8
• 12 x 2
• 6 x 4
• 4 x 6
12 square units (yellow)
• Three rectangles had an area of 12 square units:
• 6 x 2
• 3 x 4
• 12 x 1

• What is the area of this rug?

Hints

Remember, to find the area we need to multiply the length of the rectangle by the width.

Freddie and Zuri's rug is 3 units long and 3 units wide, so they need to multiply 3 x 3 to find the area.

Solution

The area of the rug is 9 square units.

The length of the rug is 3 units and the width of the rug is 3 units, so we need to multiply 3 x 3.

3 x 3 = 9, so the area is 9 square units.

• Which rectangles have the same area?

Hints

The length and the width of each rectangle is shown. Multiply these to find the area.

To figure out the area of this rectangle, we would multiply 3 x 5 to get 15.

Think about the times table facts you know to help with multiplication.

Solution

To find the area of a rectangle we multiply the length by the width.

36 square units

• 6 x 6 = 36
• 9 x 4 = 36
40 square units
• 10 x 4 = 40
• 8 x 5 = 40
42 square units
• 7 x 6 = 42
• 14 x 3 = 42
48 square units
• 12 x 4 = 48
• 8 x 6 = 48