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Pi

Revision as of 00:07, 25 June 2006 by ComplexZeta (talk | contribs) (→‎Definition)

Definition

Pi is an irrational number denoted by the greek letter $\displaystyle \pi$. It is the ratio of a circle's circumference, or perimeter, to its diameter. It is roughly equal to 3.141592653. The number pi is usually only useful when dealing with circles, spheres, and discs. The fractional approximation for pi (not exact) can be $\frac{22}{7}$. An exact formula for pi is $4\left( \sum_{i = 0}^\infty (-1)^i \left(\frac{1}{2n+1}\right)\right)$.

See Also

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