For any rectangle, area = length × width. If a rectangle is 8 cm long and 5 cm wide, its area is 8 × 5 = 40 square centimeters, written 40 cm².
The small 2 in cm² reminds us that area is measured in squares. A square with sides of 1 cm has an area of 1 cm². Lengths are in cm, but areas are in cm².
You can also split a big rectangle into two smaller ones, find each area and add them. This helps with shapes made of rectangles.
Worked example
Find the area of a rectangle 9 cm long and 7 cm wide.
- Area = length × width.
- 9 × 7 = 63.
Answer:63 cm²
Key words
- length
- the longer side
- width
- the shorter side
- cm²
- square centimeters
Practise this
New questions every time.
Common Core-referenced: 3.MD.C.7