Area of a Rectangle
Area of a rectangle.
Formula
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Example
A 4 × 6 rectangle has area A = 4×6 = 24 square units.
How it works
The area of a rectangle tells you how much flat space is inside its four sides. It works by counting how many unit squares fit across the length and how many fit up the width; multiplying those two counts gives the total number of square units. Because opposite sides of a rectangle are equal and its corners are right angles, the rows and columns of unit squares form a neat grid with no gaps or overlaps.
When to use it
Use this formula whenever you need the amount of surface inside a rectangular shape, such as a floor, a tabletop, a field, or a sheet of paper. It is also used in geometry, design, construction, and many real-world measurements.
Worked example, step by step
A rectangle is 9 cm long and 5 cm wide. Use the formula A = l × w Substitute the values: A = 9 × 5 Multiply: A = 45 So, the area is 45 cm².
Common mistakes to avoid
- Adding the length and width instead of multiplying them
- Forgetting to include square units in the final answer
- Mixing up area with perimeter, which measures distance around the shape
Did You Know?
Length times width is the definition on which the entire concept of "area" is built.
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