Find Area by Decomposing or Completing

Find Area by Decomposing or Completing

Find Area by Decomposing Rectangles

• Step 1: Use a line to break apart the figure into two rectangles

• Step 2: Find the area of each separate rectangle by multiplying the side lengths

• Step 3: Add the areas together

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Find the area of rectangle A. Write a multiplication equation with the answer to solve.

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Find the area of rectangle B. Write a multiplication equation with the answer.

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Find the area of the large figure. Add the areas together. 18 + 9

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Find the area of rectangle C. Write a multiplication equation with the answer.

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Find the area of rectangle D. Write a multiplication equation with the answer.

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Find the area of the large figure. Add the areas together 18 + 15

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Find the area of rectangle E. Write a multiplication equation including the answer.

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Find the area of rectangle F. Write a multiplication equation with the answer.

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Find the area of the large figure. Add the areas together 21 + 9

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Find the areas of rectangle G and H then add the areas together to find the total area for the figure.

Find the Area by Subtracting

• Step 1: Multiply the side lengths to find the area of the large figure.

• Step 2: Multiply the side lengths to find the area of the small figure.

• Step 3 Subtract the areas to find the area of the shaded part.

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Multiply the side lengths to find the area of the large gray figure. Write a multiplication equation with the answer.

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Multiply the side lengths to find the area of the small white figure. Write a multiplication equation with the answer.

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Subtract the areas to find the area of the shaded figure 56 - 9

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Multiply the side lengths to find the area of the large gray figure. Write a multiplication equation with the answer.

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Multiply the side lengths to find the area of the small white figure. Write a multiplication equation with the answer.

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Subtract the areas to find the area of the shaded figure 30 - 8

Finding Area by Decomposing Rectangles

• You can find area by decomposing or breaking apart a figure.

• You can multiply the side lengths of each separate rectangle to find their areas.

• You can add the areas together to find the area of the larger figure.

• This is also called Additive Area

Finding Area by Subtracting

• You can multiply to find the area of the large figure.

• You can multiply to find the area of the small figure.

• You can subtract the areas to find the area of the shaded figure.

• You can also use the rule: opposite sides of a rectangle are equal to help you solve.