In particular,cosine of alpha,I can get, well, we know how to find the angle between two vectors.
2
伏特量交流电路中电压与电流的有效值以及电流与电压之间相位角的余弦之乘积。
The product of the effective values of the voltage and current with the cosine of the phase Angle between current and voltage in an alternating-current circuit.