f（x）=3cos²x+2cosxsinx+sin²x=2cos²x+2sinxcosx+1=cos2x+sin2x+2=√2sin（2x+π/4）+2最小正周期就是T=2π/2=π单调区间单调递增区间是2x+π/4∈[2kπ-π/2,2kπ+π/2]即x∈[kπ-3π/8,kπ+π/8] k...