设函数f(x)=a*b,其中向量a=(2cos x,1),b=(cos x,根号3 sin 2x),x属于(-30,30

a·b=(2cosx,1)·(cosx,sqrt(3)sin2x)=2cosx^2+sqrt(3)sin2x=sqrt(3)sin2x+cos2x+1
=2sin(2x+π/6)+1,故：f(x)=2sin(2x+π/6)+1=3/4,即：sin(2x+π/6)=-1/8
-π/6