8.04 Area of rectangles
Are you ready?
Can you find area using a grid?
Find the area of the shape by counting the number of grid squares it covers.
Each grid square represents $1$1 square unit.
Learn
The area of a rectangle can be found using the formula:
$\text{Area}=\text{Length}\times\text{Width}$Area=Length×Width
This video shows us how we can find the area of a rectangle by multiplying its length and width together.
Apply
question 1
Find the area of the rectangle shown.
 |
width = $5$5 cm |
| length = $14$14 cm |
$\text{Area }$Area $=$= $\text{length }\times\text{width }$length ×width cm2 $\text{Area }$Area $=$= $\editable{}\times\editable{}$× cm2 (Fill in the values for the length and width.) $\text{Area }$Area $=$= $\editable{}$ cm2 (Complete the multiplication to find the area.)
Learn
A square is a special kind of rectangle, so we can use the same method to work out the area. Instead of having a different number for our length and width, each side has the same length. Markers are often used, rather than write the length on every side, as this picture shows.
Apply
Question 2
Find the area of the square shown.
 |
side length = $3$3 mm |
| side length = $3$3 mm |
$\text{Area }$Area $=$= $\text{length }\times\text{width }$length ×width mm2 $\text{Area }$Area $=$= $\text{side }\times\text{side }$side ×side mm2 (As this is a square, the values for the length
and width are the same.)$\text{Area }$Area $=$= $\editable{}\times\editable{}$× mm2 (Fill in the values for side lengths.) $\text{Area }$Area $=$= $\editable{}$ mm2 (Complete the multiplication to find the area.)
Learn
We can use the area formula to help us solve problems. If we know any two of the area, length, and width, then we can find the third value:
- We can find area by multiplying the length and width.
- We can find the length by dividing the area by the width.
- We can find the width by dividing the area by the length.
Apply
question 3
A rectangle has an area of $40$40 square units. The length of the rectangle is $8$8 units.
Find the width of the rectangle.
When we calculate area, the unit of measurement is squared. If we have sides measured in centimeters (cm), for example, the area will be cm2.