数学:函数问题6.设0x2π。且(1
6.设0x2π。且(1-sin2x)=sinx-cx.则 A.0≤x≤π B.π/4≤x≤7π/4 C.π/4≤x≤5π/4 D.π/2≤x≤3π/2
1-sin2x=sinx-cosx (sinx)^2-2sinxcosx+(cosx)^2=sinx-cosx (sinx-cosx)^2=sinx-cosx≥0 sinx-cosx≥0 √2sin(x-π/4)≥0 sin(x-π/4)≥0 π/4≤x≤5π/4 选择C