$\"\"$

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The formula for area of a circular ring is $\"\"$ .

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Solve $\"\"$ for p.

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Divide each side by $\"\"$ .

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$\"\"$

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Cancel common terms.

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

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Substitute the value of $\"\"$ in the formula $\"\"$ .

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$\"\"$

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$\"\"$

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

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The solutions $\"\"$ .