We focus on the need for azimuthal orientation angles of a system. If one azimuthal orientation angle is a function of other angles and these angles turn independently by the same axis, the sum of the partial differential of the function to the other angles is 1. We use this property of the azimuthal orientation angles turning by the same axis of the system to analyze the experimental phenomena of the terahertz polarization, and then quantum theory is used to explain the experimental phenomena.