$\"\"$

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The integral function is $\"\"$ .

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Assume $\"\"$ .

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Apply derivative on each side with respect to $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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Substitute $\"\"$ and $\"\"$ in integral function.

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$\"\"$

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Trigonometric property : $\"\"$ .

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$\"\"$

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$\"\"$

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Integration reduction fromula : $\"\"$ .

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$\"\"$

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$\"\"$ .

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Integral fromula : $\"\"$

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$\"\"$ .

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$\"\"$

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Consider $\"\"$ .

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For a right triangle, $\"\"$ and $\"\"$

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$\"\"$

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$\"\"$

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

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

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Substitute corresponding values in the equation $\"\"$ .

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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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$\"\"$ .