f(x) = √3sinxcosx-cos^2x-1/2= √3/2sin2x-(cos2x + 1)/2 - 1/2= √3/2sin2x-1/2cos2x - 1= sin2xcosπ/6-cos2xsinπ/6 - 1= sin(2x-π/6) - 1sin(2x-π/6) ≥-1f(x) = sin(2x-π/6) - 1 ≥ -2，最小值-22π/2 = π，最小正周期π
π
