设振动1为 x1=Asin(wt)振动2为 x2=Asin(wt+π/3)振动3为 x3=Asin(wt+2π/3)振动4为 x4=Asin(wt+π)上面4个式子相加，整理得：x=√3Acost选A
很明显选A
