√3 inches (x/4). cos(x/4)+cos^2(x/4)=√3/2sinx/2+ 1/2cosx/2+ 1/2

So: SIN (x/2+π/6) = 1/2, COS (x/2+π/6) =-/+√ 3/2.

cos(2π/3-x)=cos2(π/6-x/2)=cos^(π/6-x/2)-sin^(π/6-x/2)= 1/2

2，(2a-c)×cosA=b×cosC

(2sina-sinc)×cosA=sinb×cosc

Finished product sin2a-2sina*cosc=sinb*cosc, (conditions are still lacking)

F(x)=sin(x/2+π/6)+ 1/2 (the condition will be solved if we continue).