y=2sinωxcosωx+2√3cos^2ωx-√3
=sin2wx+√3cos2x
=2sin(2wx+π/3)
绝对值x1-x2的最小值为π/2,则周期T=π
T=2π/2w=π w=1
f(x)=2sin(2x+π/3)
f(a)=2sin(2a+π/3)=2/3
sin(2a+π/3)=1/3
sin(2a+π/3)=sin(π/2-(π/6-2a))=cos(π/6-2a)=1/3
sin（5π/6-4a）=sin(π/2+π/3-4a)
=cos(π/3-4a)
=2cos^2(π/6-2a)-1
=2/9-1
=-7/9