Y=2sinxcos+cos2x=sin2x+cos2x=根号2sin(2x+π/4),（化间方法根据课本和角公式例题）设2x+π/4=t,则Y=根号2sint因为0＜＝x＜＝π/2,所以0＜＝2x＜＝π,得π/4＜＝2x+π/4＜＝5π/4,即π/4＜＝t＜＝5π/4取Y=根号2sin...