Acos(wt + u) +Bcos(wt + z)

题目

Acos(wt + u) +Bcos(wt + z)
怎么化简成一个cos的函数呀

答案

Acos(wt + u) +Bcos(wt + z) ={A2+B2+2ABcos（u-z）}1/2*cos{wt-π/2+arctan-（Acosu+Bcosz)/(Asinu+Bsinz)}