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.
|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.