<P> The other way of orienting the axes is following the left hand rule, placing the left hand on the plane with the thumb pointing up . </P> <P> When pointing the thumb away from the origin along an axis towards positive, the curvature of the fingers indicates a positive rotation along that axis . </P> <P> Regardless of the rule used to orient the axes, rotating the coordinate system will preserve the orientation . Switching any two axes will reverse the orientation, but switching both will leave the orientation unchanged . </P> <P> Once the x - and y - axes are specified, they determine the line along which the z - axis should lie, but there are two possible directions on this line . The two possible coordinate systems which result are called' right - handed' and' left - handed' . The standard orientation, where the xy - plane is horizontal and the z - axis points up (and the x - and the y - axis form a positively oriented two - dimensional coordinate system in the xy - plane if observed from above the xy - plane) is called right - handed or positive . </P>

When was the cartesian coordinate system is used to describe three dimensional space