$\"\"$

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The expression is $\"\"$ .

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Sum and difference formulas : $\"\"$ .

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The expression can be written as :

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$\"\"$

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$\"\"$

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$\"\"$

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

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$\"\"$

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$\"\"$ .

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Thus, $\"\"$ . $\"\"$

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$\"\"$ .