# Difference between revisions of "Pi"

m (→Definition) |
Mathgeek2006 (talk | contribs) (→Definition) |
||

Line 1: | Line 1: | ||

== Definition == | == Definition == | ||

− | '''Pi''' is an [[irrational]] number. 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 [[circle|circles]], [[sphere|spheres]], and discs. | + | '''Pi''' is an [[irrational]] number. 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 [[circle|circles]], [[sphere|spheres]], and discs. The fractional approximation for pi (not exact) can be <math>\frac{22}{7}</math>. The exact formula for pi is <math>4\left( \sum_{i = 0}^\infty (-1)^i \left(\frac{1}{2n+1}\right)\right) </math> |

== See Also == | == See Also == | ||

*[[Circle]] | *[[Circle]] |

## Revision as of 20:46, 21 June 2006

## Definition

**Pi** is an irrational number. 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 . The exact formula for pi is