-(2cos^2x-1-2sin^2x)cos^2x 这个怎么变成 -cos^2x+4sin^2xcos^2x

化简(sin x+cos x-1)(sin x-cos x+1)/sin 2x 2cos x (sin x -cos x)+1 怎么证明2(1-sin x)(1+cos x)=(1-sin x+cos x)^2 化简 1/2cos x-根号3/2sin x 根3sin x+cos x 化简[1-(sin^4x-sin^2cos^2x+cos^4x)/(sin^2)]+3sin^2x 求证（cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2x 已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x 已知(1+sin x)/cos x=-1/2,则cos/(sin x-1)=? y=2cos x (sin x+cos x) 化简sin(x)cos(x)cos(2x) 化简sin(x)cos(x)cos(2x) sin x cos x cos 2x 化简 (sin^2x+cos^2x )(sin^2x-cos^2x)怎么得sin^2x-cos^2x? 化简 cos^2(x)*sin^2(x)-sin^2(x) 化简 cos^(2)(x)*sin^(2)(x)-sin^(2)(x) 已知sin(x)+3cos(x)=2,求sin(x)-cos(x)/sin(x)+cos(x)=? 化简sin^4x-sin^2x+cos^2x 化简:sin^4 x-sin^2 x+cos^2 x