Area of Rectangle & Complex Shapes Practice Problems

Master rectangle area calculations and decompose complex shapes into familiar rectangles. Practice with step-by-step examples and build confidence solving geometry problems.

📚Practice Calculating Areas of Rectangles and Complex Shapes
  • Calculate rectangle area using length × width formula
  • Decompose complex shapes into familiar rectangles
  • Apply rectangle properties to find missing dimensions
  • Add and subtract rectangle areas in composite shapes
  • Solve real-world rectangle area word problems
  • Master the puzzle method for complex shape areas

Understanding Area of a Rectangle

Complete explanation with examples

How do we calculate the area of complex shapes?

When students hear the words "compound shapes", they usually feel uncomfortable. Just before you also ask yourself: "Oh, why this again?", you should be aware that there is no real reason. Describing shapes as compound doesn't really make them so. As it turns out calculating areas and perimeters of compound shapes is in fact relatively straightforward.

You will be introduced to Complex shapes only after you learn various shapes in geometry. The reason these shapes are complex is due to the fact that they are slightly different from those you've come to know. In each complex shape, additional shapes that you need to identify are hidden. Dividing the complex shape into several different (and familiar) shapes will allow you to answer the question of how to calculate the area of complex shapes.

The trick: extract a familiar shape from within the complex shape

So how do we answer the question of how to calculate the area of complex shapes? First, you need to identify familiar shapes within the complex shape. An example of this: a rectangle. As you know, each shape has properties that you are familiar with, so within the complex shape itself, you can apply the properties of the familiar shape and thus calculate areas and perimeters.

After completing the missing data (according to the properties of each shape, for example: rectangle), you can complete the "puzzle", identify additional data that is revealed to you, and thus calculate the area of the complex shape. When calculating the area of complex shapes, you will often need to perform simple arithmetic operations such as division and addition (mainly for sides in the shape) - all based on the unique properties of each shape.

Two composite shapes labeled with side lengths. • Left shape: A 'house-like' figure formed by a rectangle (4 units wide and 4 units high) with a triangle on top (two equal sides of 6 units, base 4 units). • Right shape: An L-shaped polygon composed of rec

Detailed explanation

Practice Area of a Rectangle

Test your knowledge with 123 quizzes

ABCD is a rectangle.

Given in cm:

AB = 7

BC = 5

Calculate the area of the rectangle.

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Examples with solutions for Area of a Rectangle

Step-by-step solutions included
Exercise #1

AB = 10 cm

The height of the rectangle is 5 cm.

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Calculate the area of the parallelogram.

Step-by-Step Solution

To solve this problem, we'll apply the formula for the area of a parallelogram:

  • Step 1: Identify the base and the height from the given information.
  • Step 2: Use the formula for the area of a parallelogram: A=base×height A = \text{base} \times \text{height} .
  • Step 3: Calculate the area using the given values.

Let's proceed with the solution:
Step 1: The given base AB AB is 10 cm, and the height is 5 cm.
Step 2: The formula for the area of a parallelogram is A=base×height A = \text{base} \times \text{height} .
Step 3: Substituting the provided values, we get:
A=10cm×5cm A = 10 \, \text{cm} \times 5 \, \text{cm}
A=50cm2 A = 50 \, \text{cm}^2

Therefore, the area of the parallelogram is 50cm2 50 \, \text{cm}^2 .

Answer:

50

Video Solution
Exercise #2

AB = 12 cm

The height of the rectangle is 4 cm.

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Calculate the area of the parallelogram.

Step-by-Step Solution

To solve this problem, we'll proceed as follows:

  • Step 1: Identify the given values for the base and the height of the parallelogram.
  • Step 2: Apply the formula for calculating the area of the parallelogram.
  • Step 3: Calculate the area using the values provided.

Let's perform each step:

Step 1: From the problem, we know:

  • The base AB AB of the parallelogram is 12cm 12 \, \text{cm} .
  • The height relative to the base is 4cm 4 \, \text{cm} .

Step 2: Use the formula for the area of a parallelogram:

Area=base×height\text{Area} = \text{base} \times \text{height}

Step 3: Plugging in the values of the base and height:

Area=12×4=48cm2\text{Area} = 12 \times 4 = 48 \, \text{cm}^2

Therefore, the area of the parallelogram is 48cm2 48 \, \text{cm}^2 .

Since this is a multiple-choice problem, the correct answer is Choice 2.

Answer:

48

Video Solution
Exercise #3

AB = 15 cm

The height of the rectangle is 6 cm.

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Calculate the area of the parallelogram.

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the given base and height.
  • Step 2: Apply the formula for the area of a parallelogram.
  • Step 3: Calculate the area using the provided dimensions.

Now, let's work through each step:
Step 1: The base b b is equal to the length AB AB , which is 15 cm\text{15 cm}. The height h h corresponding to this base is 6 cm\text{6 cm}.
Step 2: We'll use the formula for the area of a parallelogram:
Area=b×h\text{Area} = b \times h.
Step 3: Plugging in our values, we have:
Area=15×6=90cm2\text{Area} = 15 \times 6 = 90 \, \text{cm}^2.

Therefore, the solution to the problem is Area=90cm2 \text{Area} = 90 \, \text{cm}^2 , which matches choice .

Answer:

90

Video Solution
Exercise #4

AB = 17 cm

The height of the rectangle is 8 cm.

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Calculate the area of the parallelogram.

Step-by-Step Solution

To solve this problem, we will calculate the area of the parallelogram using the given base and height dimensions.

  • Step 1: Identify the given parameters. The base of the parallelogram AB=17cm AB = 17 \, \text{cm} and the corresponding height is 8cm 8 \, \text{cm} .
  • Step 2: Apply the area formula for parallelograms: Area=base×height\text{Area} = \text{base} \times \text{height}.
  • Step 3: Substitute the given values into the formula: Area=17×8 \text{Area} = 17 \times 8 .

Calculating the product, we have:
Area=136cm2 \text{Area} = 136 \, \text{cm}^2 .

Therefore, the area of the parallelogram is 136cm2 136 \, \text{cm}^2 .

Answer:

136

Video Solution
Exercise #5

AB = 25 cm

The height of the rectangle is 13 cm.

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Calculate the area of the parallelogram.

Step-by-Step Solution

To calculate the area of the parallelogram, we'll use the formula for the area, which is the product of the base and the height.

  • Identify the base and height from the information given: The base AB AB is 25 cm and the height is 13 cm.
  • Apply the formula for the area: Area=Base×Height\text{Area} = \text{Base} \times \text{Height}.
  • Substitute the given values into the formula: Area=25×13\text{Area} = 25 \times 13.
  • Perform the multiplication: Area=325\text{Area} = 325 square centimeters.

Therefore, the area of the parallelogram is 325cm2 325 \, \text{cm}^2 .

This corresponds to choice 1: 325.

Answer:

325

Video Solution

Frequently Asked Questions

How do you find the area of a rectangle?

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The area of a rectangle is calculated using the formula: Area = length × width. Simply multiply the length by the width to get the total area in square units.

What is the easiest way to find the area of complex shapes?

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Break down complex shapes into familiar shapes like rectangles. Identify the rectangles within the complex shape, calculate each rectangle's area separately, then add or subtract these areas as needed.

How do you calculate missing dimensions in rectangle problems?

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Use the properties of rectangles: opposite sides are equal. If you know some dimensions, use addition and subtraction to find missing measurements based on the overall shape dimensions.

What are composite shapes in geometry?

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Composite shapes (also called compound shapes) are figures made up of two or more basic shapes combined together. They can be solved by breaking them into rectangles, triangles, or other familiar shapes.

Why do students struggle with complex shape area problems?

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Students often feel overwhelmed because complex shapes look complicated. The key is recognizing that these are just combinations of simple shapes you already know how to solve.

What math operations are needed for rectangle area problems?

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You'll primarily use: 1) Multiplication (length × width), 2) Addition (combining areas), 3) Subtraction (removing overlapping areas), 4) Basic arithmetic to find missing dimensions.

How do you solve L-shaped area problems?

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Divide the L-shape into two rectangles. Calculate each rectangle's area using length × width, then add the two areas together for the total area of the L-shaped figure.

What are common mistakes when calculating rectangle areas?

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Common errors include: mixing up length and width, forgetting to include units, adding dimensions instead of multiplying them, and not properly identifying rectangles within complex shapes.

More Area of a Rectangle Questions

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Practice by Question Type

Applying the formula Calculate The Missing Side based on the formula Calculation using percentages Finding Area based off Perimeter and Vice Versa Identifying and defining elements Subtraction or addition to a larger shape Using additional geometric shapes Using external height Using Pythagoras' theorem Using ratios for calculation Using variables Verifying whether or not the formula is applicable Applying the formula Calculate The Missing Side based on the formula Calculating in two ways Finding Area based off Perimeter and Vice Versa Using additional geometric shapes Using congruence and similarity Using external height Using Pythagoras' theorem Using ratios for calculation Using variables Verifying whether or not the formula is applicable Applying the formula A shape consisting of several shapes (requiring the same formula) Calculate The Missing Side based on the formula Calculation using the diagonal Extended distributive law Finding Area based off Perimeter and Vice Versa Subtraction or addition to a larger shape Using additional geometric shapes Using Pythagoras' theorem Using ratios for calculation Using short multiplication formulas Using variables Worded problems Applying the formula Calculate The Missing Side based on the formula Finding Area based off Perimeter and Vice Versa Subtraction or addition to a larger shape Suggesting options for terms when the formula result is known Using additional geometric shapes Using Pythagoras' theorem Using ratios for calculation Using variables Applying the formula Ascertaining whether or not there are errors in the data Calculate The Missing Side based on the formula Calculating in two ways Extended distributive law Finding Area based off Perimeter and Vice Versa How many times does the shape fit inside of another shape? Identifying and defining elements Subtraction or addition to a larger shape Using additional geometric shapes Using congruence and similarity Using Pythagoras' theorem Using ratios for calculation Using variables Worded problems