Find the circumference of each circle from the given radius or diameter

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The clayton family’s pool has vertices at the coordinates (0, 2), (0, 5), (2, 5), (2, 6), (5, 6), (5, 1), (2, 1), and (2, 2). if each grid square has an area of 9 square feet, what is the area of the pool?

Can someone show me step by step how to do this?

Which number produces an irrational number multiplied by 1/3