cos(-16π/3)+sin(-16π/3)=cos(-6π+2π/3)+sin(-6π+2π/3)
=cos(2π/3)+sin(2π/3)=cos(π-π/3)+sin(π-π/3)
=-cos(π/3)+sin(π/3)
=-1/2+√3/2
=（√3-1）/2