$\"\"$

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The vector is $\"\"$ and $\"\"$ .

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Find r.

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$\"\"$

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(a)

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The equation is $\"\"$ .

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Consider $\"\"$ .

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$\"\"$

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

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Therefore, $\"\"$ .

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$\"\"$

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(b)

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The equation is $\"\"$ .

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Consider $\"\"$ .

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$\"\"$

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Therefore, $\"\"$ .

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$\"\"$

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(c)

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The equation is $\"\"$ .

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Consider $\"\"$ .

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$\"\"$

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Apply chain rule of partial derivatives : $\"\"$ .

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$\"\"$

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Substitute $\"\"$ in above equation.

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$\"\"$

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Therefore, $\"\"$ .

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$\"\"$

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(d)

\

The equation is $\"\"$ .

\

Consider $\"\"$ .

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$\"\"$

\

Apply chain rule of partial derivatives : $\"\"$ .

\

$\"\"$

\

Substitute $\"\"$ in above equation.

\

$\"\"$

\

Therefore, $\"\"$ .

\

$\"\"$

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(a) $\"\"$ .

\

(b) $\"\"$

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(c) $\"\"$

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(d) $\"\"$ .