$\"\"$

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The expression is $\"\"$ .

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Rewrite the expression as $\"\"$ .

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Co-function identity : $\"\"$ .

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$\"\"$

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Pythagorean identity : $\"\"$ .

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$\"\"$

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Therefore, the exact value of $\"\"$ is $\"\"$ .

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$\"\"$

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The exact value of $\"\"$ is $\"\"$ .