$\"\"$

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The parametric equations are $\"\"$ and $\"\"$ .

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The function is $\"\"$ and $\"\"$ .

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Substitute $\"\"$ and $\"\"$ in above equation.

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$\"\"$

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

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$\"\"$

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$\"\"$ .

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Substitute $\"\"$ in above equation.

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$\"\"$

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At $\"\"$ the value of $\"\"$ .

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$\"\"$ \ \

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The function is $\"\"$ .

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

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$\"\"$

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$\"\"$ .

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Substitute $\"\"$ in above equation.

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$\"\"$

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At $\"\"$ the value of $\"\"$ .

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$\"\"$

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$\"\"$ , 0.

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$\"\"$ , 0.