$\"\"$

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The function is $\"\"$ then prove that $\"\"$ .

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Rewrite the above equation.

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$\"\"$

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Since trigonometry identity : $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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Definition of hyperbolic trigonometry : $\"\"$ .

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hence $\"\"$ .

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$\"\"$

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$\"\"$ .