what is pi

Pi (π) is a mathematical constant that represents the ratio of a circle's circumference to its diameter, approximately equal to 3.14159.

Definition. It is defined as the circumference of a circle divided by its diameter (π = C/d). This ratio is the same for every circle, regardless of its size.
Mathematical Properties. Pi is an irrational number, meaning it cannot be expressed as a simple fraction, and its decimal digits go on forever without a repeating pattern. It is also a transcendental number.
History of Notation. The symbol π was first used to represent this ratio by Welsh mathematician William Jones in 1706 and was later popularized by Leonhard Euler.
Common Applications. Pi is essential in geometry and physics, appearing in formulas for the circumference (C=2πr), area (A=πr²), and volume of spheres (V=4/3πr³).

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