An

*n*-tuple having two elements.As with all n-tuples, the order of the elements of an ordered pair is important, as it expresses a relationship from

*a*to*b*, in the case of the ordered pair (*a*,*b*). The first element is called the**first coordinate**of the ordered pair and the second element is called**second coordinate**of the ordered pair.### Notation

The ordered pair with first coordinate *a* and second coordinate *b* is written as : (*a*, *b*).

### Properties

- An ordered pair whose two components are the same is called an
**identical ordered pair**. - There ordered pair (
*b*,*a*) is called the reciprocal ordered pair or the symmetric ordered pair of the ordered pair (*a*,*b*).

### Examples

- The ordered pair (5, 12).
- The ordered pair (5,034; –8,1).
- The ordered pair (5, 5) is an identical ordered pair.
- The ordered pairs (2, −3) and (−3, 2) are reciprocal or symmetric ordered pairs.