$\"\"$

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(a).

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Write $\"\"$ as a function of $\"\"$ .

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Observe the figure :

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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(b).

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When $\"\"$ find $\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ .

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When $\"\"$ find $\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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(a). $\"\"$

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(b). $\"\"$ and $\"\"$ .