fx=sin（π-x）sin（π／2-x）+cos²x =sinxcosx+cos²x=1/2sin2x+1/2cos2x+1/2=√2/2(sin2xcosπ/4+cos2xsinπ/4)+1/2=√2/2sin(2x+π/4)+1/2最小正周期 2π/2=π当x属于[-π/8,3π/8]时0≤2x+π/4≤πf(...