The expression is $\"\"$ .

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Trigonometric identity : $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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Multiply 2 with numerator and denominator.

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$\"\"$

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Double angle identity : $\"\"$ .

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$\"\"$

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Multiply cos y with numerator and denominator.

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$\"\"$

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Pythagorean identity : $\"\"$ .

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$\"\"$

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$\"\"$

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Multiply 2 with numerator and denominator.

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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

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