Difference between revisions of "Pi"
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== Definition == | == Definition == | ||
| − | '''Pi''' is an [[irrational]] number denoted by the greek letter <math>\displaystyle \pi </math>. 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>. | + | '''Pi''' is an [[irrational]] number denoted by the greek letter <math>\displaystyle \pi </math>. 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>. An 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 23:07, 24 June 2006
Definition
Pi is an irrational number denoted by the greek letter 
. 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 
. An exact formula for pi is 
.
