System whose rectilinear axes cross at the origin of the coordinates.

The coordinates of a point in a Cartesian system are called Cartesian coordinates. If the axes are perpendicular, the coordinates of the points of the system are called

**rectangular coordinates**.

### Properties

If the axes are perpendicular, the Cartesian system is orthogonal. If the axes have the same intervals and the same norm, then the axes are said to be normalized, and the Cartesian system made up of these axes is normalized.

### Example

This is a Cartesian system in which the axes are orthogonal but not normalized :

Therefore, this is not a Cartesian plane.