$\"\"$

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The expression is $\"\"$ .

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Rewrite the expression.

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$\"\"$

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The expression $\"\"$ is in the form of $\"\"$ .

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$\"\"$ can be written as $\"\"$ .

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$\"\"$

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Pythagorean identities : $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$