<P> A commonly used mnemonic for defining the positive orientation is the right hand rule . Placing a somewhat closed right hand on the plane with the thumb pointing up, the fingers point from the x-axis to the y - axis, in a positively oriented coordinate system . </P> <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>

Where does the word cartesian plane come from