Trying to measure the distance around a circle's circumference can be difficult since a ruler will snap before it bends into a circle and measuring tape cannot match a circle's perfect roundness. The solution to figuring the circumference lies with the mathematical constant pi, 3.142 when rounded, and the circle's diameter. By finding the circle's radius, which is half of the diameter's length and the distance from the circle's center to any point on the circumference, you can figure the length of the circle's circumference through the equation circumference = pi * diameter.
Instructions
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1
Measure the distance from the circle's center to its circumference to calculate its radius. For an example, the radius measures 4 inches.
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2
Multiply the radius by 2 to calculate the diameter's length --- 4 inches multiplied by 2 equals 8 inches.
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3
Multiply pi to the diameter's length to figure the circle's circumference --- 8 inches multiplied by 3.142 equals approximately 25.133 inches.