y=sin平方x+sin2x+3cos平方x=1+sin2x+2cos^2x=1+sin2x+2cos^2x-1+1=sin2x+cos2x+2=√2sin(2x+π/4)+2当 sin(2x+π/4)=-1 时 函数的最小值=2-√2此时 2x+π/4=2kπ-π/2 x=kπ-3π/8函数的单调减区间2kπ-π/2...