$\"\"$

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The trigonometric identity is $\"open$ .

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Consider $\"\"$ .

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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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$\"\"$

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$\"equal$

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

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$\"equal$

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$\"\"$ \ \

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$\"equal$

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$\"open$ .

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$\"\"$

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$\"open$ .

\