〈AOB=π/3-π/6=π/6,OA=OB=3,根据余弦定理,AB^2=OA^2+OB^2-2*OA*OB*cos(π/6),AB^2=18-9√3,|AB|=3（√6-√2）/2.也可转换成直角坐标,x=ρcosθ,y=ρsinθ,ρ=3,θ=π/3,A（3/2,3√3/2）,θ=π/6,B（3√3/2,3/2）,...