f(x)=（sin^4x+cos^4x+sin²xcos²x）/（2-2sinxcosx）-（sinxcosx）/（2）+（cos2x/4）
=（sin^4x+cos^4x+2sin²xcos²x-sin²xcos²x）/（2-2sinxcosx）-1/4*sin2x+1/4*cos2x
=[(sin²x+cos²x)²-sin²xcos²x）/（2-2sinxcosx）-1/4*sin2x+1/4*cos2x
=(1-sin²xcos²x）/（2-2sinxcosx）-1/4*sin2x+1/4*cos2x
=(1-sinxcosx)(1+sinxcosx)/2(1-sinxcosx)-1/4*sin2x+1/4*cos2x
=(1+sinxcosx)/2-1/4*sin2x+1/4*cos2x
=1/2+1/4*sin2x-1/4*sin2x+1/4*cos2x
=1/2+1/4*cos2x
T=2π/2=π
-1