sin(pi/3-a)=sin(pi/3)*cos(a)-sin(a)*cos(pi/3)=sqrt(3)/2 * (-5/13) - sqrt(1-cos(a)^2)*0.5=
= -5*sqrt(3)/26 -sqrt(1-25/169)*0.5= -5*sqrt(3)/26 - 6/13,это?
sin(pi/3-a)=sin(pi/3)*cos(a)-sin(a)*cos(pi/3)=sqrt(3)/2 * (-5/13) - sqrt(1-cos(a)^2)*0.5=
= -5*sqrt(3)/26 -sqrt(1-25/169)*0.5= -5*sqrt(3)/26 - 6/13,это?