int (sin^8x-cos^8x)/(1-2sin^2xcos^2x)dx
=int ((sin^4x+cos^4x)(sin^4x-cos^4x))/((sin^2x+cos^2x)^2-2sin^2xcos^2x)dx
=int ((sin^4x+cos^4x)(sin^4x-cos^4x))/(sin^4x+cos^4x)dx
=int (sin^4x-cos^4x)dx
=int (sin^2x-cos^2x)(sin^2x+cos^2x)dx
=int (sin^2x-cos^2x)dx
=-intcos2xdx
=-1/2sin2x