The angles which specify the relative orientation of the two coordinate systems are called Euler's angles. They are defined by the following rules. First
a clockwise rotation around the -axis is performed. This angle is usually denoted as . Then a clockwise rotation around the new -axis
follows. This second angle is denoted as . Finally, a clockwise rotation around the new -axis finishes the transformation. The last angle is
denoted as . The range of these angles are determined as follows: