$\"\"$

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The trigonometric expression is $\"\"$ .

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$\"\"$ .

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Apply tigonometric reciprocal identity: $\"\"$ .

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$\"\"$ .

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$\"\"$ is in second quadrant, $\"\"$ .

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Apply half-angle formula: $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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Substitute $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$ .

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$\"\"$

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$\"\"$ .