$\"\"$

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The trignometry expression is $\"\"$ .

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Let $\"\"$

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

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Where $\"\"$ lies in second quadrant.

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Find $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Apply the inverse trigonometric identity: $\"\"$ where $\"\"$ .

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$\"\"$

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The exact value of $\"\"$ .

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$\"\"$

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$\"\"$ .