Rectangle Area Calculation: Using Perimeter of 30 and Width of 5

Rectangle Properties with Given Perimeter

The perimeter of the rectangle below is equal to 30.

What is the area of the rectangle?

101010555AAABBBDDDCCC

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1

Understand the problem

The perimeter of the rectangle below is equal to 30.

What is the area of the rectangle?

101010555AAABBBDDDCCC

2

Step-by-step solution

We use the formula to calculate the area of a rectangle: length times width:

AC×AB=S AC\times AB=S

We replace the existing data:

5×10=50 5\times10=50

That is, the information that the perimeter of the rectangle is equal to 30 is unnecessary, since all the data to calculate the area already exist and it is not necessary to calculate the other sides.

3

Final Answer

50

Key Points to Remember

Essential concepts to master this topic
  • Formula: Rectangle area equals length times width (A = l × w)
  • Technique: Use given dimensions directly: 10 × 5 = 50
  • Check: Verify perimeter: 2(10) + 2(5) = 30 matches given value ✓

Common Mistakes

Avoid these frequent errors
  • Using perimeter formula to calculate area
    Don't try to use P = 2l + 2w to find area directly = confusion and wrong calculations! The perimeter gives you missing dimensions, but when both length and width are already shown, use them directly. Always identify what information you actually need for the specific question.

Practice Quiz

Test your knowledge with interactive questions

Look at the rectangle ABCD below.

Side AB is 6 cm long and side BC is 4 cm long.

What is the area of the rectangle?
666444AAABBBCCCDDD

FAQ

Everything you need to know about this question

Why is the perimeter information not needed here?

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The diagram already shows both dimensions: length = 10 and width = 5. Since area only needs length × width, you have everything required! The perimeter is extra information.

How do I know which dimension is length and which is width?

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For rectangles, it doesn't matter! Whether you call it 10 × 5 or 5 × 10, the area is still 50. Length and width are just labels for the two different sides.

What if only the perimeter was given?

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Then you'd need one more piece of information (like one side length) to find the other side. With perimeter alone, there are infinite possible rectangles!

Should I always check if the perimeter makes sense?

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Yes! It's a great way to verify your dimensions are correct. Calculate P = 2l + 2w and see if it matches any given perimeter value.

What's the difference between area and perimeter?

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Area measures the space inside (length × width), while perimeter measures the distance around the outside (2l + 2w). Think: area fills, perimeter surrounds!

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