=lim(x→П/6)(1-2sinx)/(cosx(4cos^2x-3))=
=lim(x→П/6)(1-2sinx)/cosx(1-4sin^2x)=
=lim(x→П/6)1/cosx(1+2sinx)=1/((√3/2)(2)=1/√3=√3/3
ответ √3/3
