7.4.5 Rotating about an Axis
The above rotations were relative to the x -, y- and z -axes. Now let’s consider
rotations about an axis parallel to one of these axes. To begin with, we will
rotate about an axis parallel with the z -axis, as shown in Figure 7.14. The
scenario is very reminiscent of the 2D case for rotating a point about an
arbitrary point, and the general transform is given by