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The limit expression is $\"\"$ .

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Definition of the hyperbolic functions: $\"\"$ .

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$\"\"$ $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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This is an indeterminate form.

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Apply L $\"\"$ Hospital $\"\"$ s Rule: $\"\"$ .

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