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The Area A of a circular ring is $\"\"$

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$\"\"$ (Divide each side by W)

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$\"\"$ (Divide each side by $\"\"$ )

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Multiply: $\"\"$ )

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$\"\"$ (Cancel common terms)

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$\"\"$ (Use calculator) $\"\"$

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The radius r of a circular ring is $\"\"$

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