$\"\"$

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The trigonometric expression is $\"\"$ .

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$\"\"$ (Write original expression)

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$\"\"$ (Apply product - to - sum formula: $\"\"$ )

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$\"\"$ (Apply LCM rule: $\"\"$ )

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$\"\"$ (Simplify)

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$\"\"$ (Apply odd identity: $\"\"$ ) $\"\"$

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The solution is $\"\"$ .