f(x)=sinxcosx-√3cos(π+x)cosx
＝1/2 *2sinxcosx -√3*(-cosx)cosx
=1/2 *sin2x +√3*(1+cos2x)/2
=√3/2*cos2x +1/2 *sin2x +√3/2
=cos(2x-π/6) +√3/2
所以余弦型函数f(x)的最小正周期是T=2π/2=π