2*sqrt(3)*cos(2p/3)-2*cos(p/6)=
cos(2p/3)=-cos(p/3 )=-1/2 cos(p/6)=sqrt(3)/2
= -sqrt(3)-sqrt(3)=-2sqrt(3)
2*sqrt(3)*cos(2p/3)-2*cos(p/6)=
cos(2p/3)=-cos(p/3 )=-1/2 cos(p/6)=sqrt(3)/2
= -sqrt(3)-sqrt(3)=-2sqrt(3)