# rectangular coordinates

Axes used in rectangular coordinate systems. Those
in the top illustration are used in plane geometry, the *x*-axis
being at right angles to the *y*-axis. Those in the bottom
illustration are for use in three dimensions, the *x*-, *y*,
and *z*-axes being at mutual right angles.

Rectangular coordinates are a set of coordinates that
gives the position of an object with respect to two or three mutually perpendicular
axes (*x*, *y*, and *z*) that cross at some specified origin.
In astronomy, heliocentric or geocentric rectangular coordinates are occasionally
used to give positions of bodies in the Solar System.