$\"\"$

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The integral is $\"\"$ .

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Subustiute $\"\"$ , $\"\"$ .

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$\"\"$

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Limits of integration change from $\"\"$ to $\"\"$ to $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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From the pythagorean identity : $\"\"$ .

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$\"\"$

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From the reciprocal identitites : $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .