It need to be at least 50 ft long and 50 ft wide.
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Formula
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Area of circle = πr²
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Find radius
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πr² = 75
r² = 75 ÷ π
r² = 23.87
r = √23.87
r = 4.89 cm (nearest hundreds)
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Answer : radius = 4.89cm
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Check the attached file and let me know what you think.