正弦量的向量表示法：A=a+jb
=rcosα+jrsinα
=re^jα
或简写为：A=r∠α (必须牢记!)
则正弦电压u=Um*sin(ωt+α)的向量式为：
u=U(cosα+jsinα)
所以：e1=110sin314t
=110cos0°+j110sin0°
e2=110sin(314t+120°)
=110cos120°+j110sin120°
所以：e1+e2=110cos0°+j100sin0°
+
110cos120°+jsin120°
=(110+j0)+(-55+j110*0.866)V
=55+j95.26
=110e^j60°
所以：e1+e2=110sin(314t+60°)
e1-e2就你自己算了嘛1