Calculate Rectangle Area: 4.5 cm × 2 cm Geometric Problem

Rectangle Area with Decimal Dimensions

Look at the rectangle ABCD below.

Side AB is 4.5 cm long and side BC is 2 cm long.

What is the area of the rectangle?
4.54.54.5222AAABBBCCCDDD

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Apply the formula for the area of a rectangle
00:07 Substitute the relevant data into the formula
00:10 That's the solution!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Look at the rectangle ABCD below.

Side AB is 4.5 cm long and side BC is 2 cm long.

What is the area of the rectangle?
4.54.54.5222AAABBBCCCDDD

2

Step-by-step solution

We begin by multiplying side AB by side BC

We then substitute the given data and we obtain the following:

4.5×2=9 4.5\times2=9

Hence the area of rectangle ABCD equals 9

3

Final Answer

9 cm²

Key Points to Remember

Essential concepts to master this topic
  • Formula: Area of rectangle = length × width
  • Calculation: Multiply 4.5 cm × 2 cm = 9 cm²
  • Check: Units should be square units (cm²) and answer makes sense ✓

Common Mistakes

Avoid these frequent errors
  • Adding the sides instead of multiplying
    Don't add 4.5 + 2 = 6.5 cm! This gives perimeter, not area, and has wrong units. Always multiply length × width for rectangle area.

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 do we multiply the sides instead of adding them?

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Adding gives you the perimeter (distance around), but area measures the space inside. Think of tiling: you need 4.5 × 2 = 9 square tiles to fill this rectangle!

What if I get confused about which sides to multiply?

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For rectangles, it doesn't matter! Length × width gives the same result as width × length. Just pick any two adjacent sides (sides that meet at a corner).

Why is my answer in cm² instead of just cm?

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Area is always measured in square units! When you multiply cm × cm, you get cm². This tells us we're measuring a 2-dimensional space, not just a length.

How do I multiply 4.5 × 2 without a calculator?

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Think of 4.5 as 4½. So 4½ × 2 = (4 × 2) + (½ × 2) = 8 + 1 = 9. Or use 4.5×2=4510×2=9010=9 4.5 \times 2 = \frac{45}{10} \times 2 = \frac{90}{10} = 9

What if the rectangle had different dimensions?

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The method stays the same! Always use Area = length × width. Whether the sides are 3 cm and 7 cm, or 2.8 cm and 5.1 cm, just multiply them together.

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