# Ordered Pair

Pronunciation: /ˈɔr.dərd pɛər/ Explain

 Click on the blue point and drag it to change the figure. Why does (3,2) mean something different from (2,3)? Manipulative 1 - Ordered Pair Created with GeoGebra.

An ordered pair is a pair of values where the order is significant. This means that the ordered pair (a, b) may not be the same as the ordered pair (b, a).

Ordered pairs are usually written in the form (a, b). The form <a, b> is sometimes used to avoid conflict with other uses of the notation (a ,b). Ordered pairs are used to define the terms function and relation.

The first entry in an ordered pair is the abscissa. The second entry an ordered pair is the ordinate. The plural of abscissa is abscissae. In the ordered pair (4, -2), the abscissa is 4 and the ordinate is -2.

### Equality of Ordered Pairs

Two ordered pairs are equal if and only if their corresponding elements are equal: (a1, b1) = (a2, b2) if and only if a1 = a2 and b1 = b2.

### Ordered Triples

An ordered triple is a set of three numbers where order matters. Ordered triples are used, among other things, to define a point in a three dimensional Cartesian space. An example of an ordered triple is (x0, y0, z0).

### References

1. McAdams, David E.. All Math Words Dictionary, ordered pair. 2nd Classroom edition 20150108-4799968. pg 131. Life is a Story Problem LLC. January 8, 2015. Buy the book

### Cite this article as:

McAdams, David E. Ordered Pair. 4/27/2019. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/o/orderedpair.html.

### Revision History

4/27/2019: Changed equations and expressions to new format. (McAdams, David E.)
12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
9/5/2018: Removed broken links, updated license, implemented new Geogebra protocol, implemented new markup. (McAdams, David E.)
8/7/2018: Changed vocabulary links to WORDLINK format. (McAdams, David E.)
3/15/2010: Added section on "Ordered Triple". (McAdams, David E.)
12/21/2009: Added "References". (McAdams, David E.)
10/25/2009: Added information on abscissa, ordinate, and equality. (McAdams, David E.)
10/8/2008: Added manipulative 1. (McAdams, David E.)
3/22/2008: Added where ordered pairs are used. (McAdams, David E.)
7/12/2007: Initial version. (McAdams, David E.)

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