Circumference and area of circles

A circle's circumference (distance around it) is found with C = 2 x pi x r, and its area is found with A = pi x r^2, where r is the radius and pi is about 3.14. For a circle with radius 5, the circumference is about 2 x 3.14 x 5 = 31.4, and the area is about 3.14 x 5^2 = 78.5.

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