sin^4x cos^2x+cos^4x sin^2 x=sin^2x*cot^2x 怎么得来
(sin^2x+cos^2x )(sin^2x-cos^2x)怎么得sin^2x-cos^2x?
已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x
证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4
化简sin(派-x)+sin(派+x)-cos(-x)+cos(2派-x)-tan(派+x)cot(派-x)
sin^2x+cos^2x)(sin^4x-sin^2xcos^2x+cos^4x) =sin^4x-sin^2xcos
求证(cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2
化简[1-(sin^4x-sin^2cos^2x+cos^4x)/(sin^2)]+3sin^2x
用cos x表示sin^4 x -sin^2 x +cos^2 x
求导f(x) = cos(3x) * cos(2x) + sin(3x) * sin(2x).
(1-(sin^4x-sin^2xcos^2x+cos^4x)/sin^2x +3sin^2x
已知函数f(x)=cos^4 x-2sin x cos x-sin^4 x
化简 cos^2(x)*sin^2(x)-sin^2(x)