Acos2π(t/T-x/λ)+Acos[2π(t/T+x/λ)+π]=Acos2π(t/T-x/λ)-Acos2π(t/T+x/λ)=A[cos2π(t/T-x/λ)-cos2π(t/T+x/λ)]=2Asin(2πt/T)sin(2πx/λ).(和差化积)这是您要的吗?