$\"\"$

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The given expression is $\"\"$ .

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= $\"\"$

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$\"\"$

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The solution is $\"\"$ .

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$\"\"$

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The given trigonometric expression is $\"\"$ .

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$\"\"$

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Apply pythagorean identity: $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ (The ratio identity: $\"\"$ ) $\"\"$

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The solution is $\"\"$ .