$\"\"$

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Observe the diagram :

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One side of the cube is $\"\"$ ,.

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Let $\"\"$ .

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Find the surface area :

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The surface area of the cube is $\"\"$ .

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

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$\"\"$ ( $\"\"$ )

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$\"\"$ .

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

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$\"\"$

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