$\"\"$

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The trigonometric identity is $\"\"$ .

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Consider $\"\"$ .

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Quotient identities: $\"\"$ and $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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Apply Pythagorean identity: $\"Syntax$ .

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$\"\"$

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$\"\"$

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Apply double-angle formula: $\"italic$ .

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$\"equal$

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$\"\"$ .

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$\"\"$

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$\"\"$ .