$\"\"$

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Observe the figure:

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The length of the rectangle is $\"\"$ .

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The width of the rectangle is $\"\"$ .

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Hence the area of the rectangle is $\"\"$ .

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$\"\"$ (Substitute $\"\"$ and $\"\"$ )

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$\"\"$ (Distributive property: $\"\"$ )

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$\"\"$ (Factor constants)

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$\"\"$ (Product property of radicals: $\"\"$ )

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$\"\"$ (Simplify)

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Therefore, the area of the rectangle is $\"\"$ .

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$\"\"$

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The area of the rectangle is $\"\"$ .