已知f(x)=(sinx+cosx)²/(2+2sin2x-cos²2x),若

已知f(x)=(sinx+cosx)²/(2+2sin2x-cos²2x),若
已知f(x)=(sinx+cosx)²/(2+2sin2x-cos²2x),若

已知f(x)=(sinx+cosx)²/(2+2sin2x-cos²2x),若
f(x)=(1+2sinxcosx)/(1+2sin2x+sin²2x)
=(1+sin2x)/(1+sin2x)²
=1/(1+sin2x)
∵f(3π/8+α/2)=13/18
∴1/[1+sin(3π/4+α)]=13/18
sin(3π/4+α)=5/13
∵0