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The trigonometric function is $\"\"$ .

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$\"\"$ .

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Apply formula : $\"\"$ .

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$\"\"$

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$\"\"$ $\"\"$ .

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The different quotient is $\"\"$ .

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$\"\"$ $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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

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$\"\"$ $\"\"$ $\"\"$ .