1-cos2x+sin2x=sin2x-cos2x+1=(√2)[(√2/2)sin2x-(√2/2)cos2x]+1【(√2)×(√2/2)=2/2=1】=(√2)[sin2xcos(π/4)-cos2xsin(π/4)]+1=(√2)sin(2x-π/4)+1【用了公式：sin(α-β)=sinαcosβ-cosαsinβ】...