$\"\"$

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The trigonometric expression is $\"\"$ and let $\"\"$ .

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$\"\"$ (Write original expression)

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Apply formula: $\"\"$ )

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$\"\"$ (Apply inverse formula: $\"\"$ )

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$

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The solution is $\"\"$ .