f(x)=cos^2x+2√3sinxcosx-sin^2x =cos^2x-sin^2x+2√3sinxcosx =cos2x+2√3sinxcosx =cos2x+√3sin2x =2[(1/2)*cos2x+(√3/2)*sin2x] =2*sin(2x+π/6) =2*sin[2(x+π/12)]周期为2π/2=π单调区间为:[kπ-π/3,kπ+π/6)上单调增;[kπ+π/6,kπ+2π/3)上单调减。