# Difference between revisions of "Centre (mathematics)"

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* In an algebraic structure, elements that commute with every element of the structure | * In an algebraic structure, elements that commute with every element of the structure | ||

** The [[centre of a group]], elements that commute with every group element | ** The [[centre of a group]], elements that commute with every group element | ||

− | * The centre of a [[circle]] | + | * The centre of a [[Circle (mathematics)|circle]] |

* The centre of mass, centroid or [[barycentre]] of a geometrical figure | * The centre of mass, centroid or [[barycentre]] of a geometrical figure | ||

* In [[triangle geometry]] | * In [[triangle geometry]] | ||

− | ** The [[centroid]], intersection of the [[median]]s | + | ** The [[centroid]], intersection of the [[median (gemotry)|median]]s |

** The [[circumcentre]], intersection of the [[perpendicular bisector]]s of the sides, centre of the circle through the vertices | ** The [[circumcentre]], intersection of the [[perpendicular bisector]]s of the sides, centre of the circle through the vertices | ||

** The [[nine-point centre]] | ** The [[nine-point centre]] |

## Revision as of 18:04, 23 November 2008

In mathematics, **centre** may refer to:

- In an algebraic structure, elements that commute with every element of the structure
- The centre of a group, elements that commute with every group element

- The centre of a circle
- The centre of mass, centroid or barycentre of a geometrical figure
- In triangle geometry
- The centroid, intersection of the medians
- The circumcentre, intersection of the perpendicular bisectors of the sides, centre of the circle through the vertices
- The nine-point centre
- The orthocentre, intersection of the altitudes
- The incentre, centre of a circle tangent to the sides
- The excentres, centres of the three circles internally tangent to one side and externally to the other two