A,B的极坐标分别为(3,π/3)和(3,7/6π),根据余弦定理|AB|^2=|OA|^2+|OB|^2-2|OA||OB|cos∠AOB =9+9-2*9*cos(7π/6-π/3) =18-18*(-√3/2) =18+9√3∴|AB|=√(18+9√3)=3(√6+√2)/2...