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# Who invented the circle?

Since circular creations appear throughout nature, no man can be credited with the invention of the circle. From the cross-section of a plant stem to the moon and the sun, circles appear everywhere in nature.

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Ancient mathematicians, astronomers and engineers observed, measured and were inspired by the circle. Egyptian engineers used methods to compute areas and volumes for circles. As early as 1700 B.C., the Rhind papyrus records a method to find the area of a circular field. Written in 300 B.C., “Book 3” of Euclid's “Elements” deals with the characteristics of circles. Plato's “Seventh Letter” presents a detailed definition and explanation of the circle and the author’s conclusion that no one has ever seen a perfect circle, only approximations.

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## Why is pi important?

A: If the circumference or the area of a circle is known, pi can be used to find the diameter and the radius of that circle. Likewise, if the radius or diamet... Full Answer >Filed Under: -
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## What is the formula for radius?

A: The formula for a radius is the diameter of a circle divided by two. The radius of a circle is defined as the distance from the middle of a circle to any p... Full Answer >Filed Under: -
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## What is the difference between a circle and an ellipse?

A: A circle is actually a special kind of ellipse where the two focuses are equal. Every ellipse contains two points called a focus. The perimeter of the elli... Full Answer >Filed Under: -
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## What is the formula for the circumference of a circle?

A: The formula for circumference of a circle is 2πr, where “r” is the radius of the circle and the value of π is approximately 22/7 or 3.14. The circumference... Full Answer >Filed Under: