$\"\"$

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The expression is $\"\"$ .

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$\"\"$ (Apply Trigonometric identity)

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$\"\"$ (Subtract $\"\"$ from each side)

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$\"\"$ (Simplify)

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

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$\"\"$ (Evaluate power: $\"\"$ )

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$\"\"$ (Subtract: $\"\"$ )

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$\"\"$ (Take the square root of each side)

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$\"\"$ (Simplify)

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$\"\"$ is in the second quadrant, cos $\"\"$ is negative,

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Therefore $\"\"$ . $\"\"$

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To find tan $\"\"$ .

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$\"\"$

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

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$\"\"$ (Cancel common terms)

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$\"\"$ (Multiply numerator and denominator by $\"\"$ )

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$\"\"$ (Multiply) $\"\"$

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The value of $\"\"$ .