$\"\"$

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Radius (r) of the circle is given by $\"\"$ .

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ZW be the diameter (d) of the circle R.

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$\"\"$

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$\"\"$ (Multiply each side by 2)

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

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

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The value of $\"\"$ .