求证：cos3xcosx+sin^22x=sin3xsinx+cos^22x.

求证：cos3xcosx+sin^22x=sin3xsinx+cos^22x. 求证：cos3xcosx+sin^22x=sin3xsinx+cos^22x 求证：cos4x+cos2x=cos3xcosx 求证sin²x-sin²y=sin(x+y)sin(x-y) 求证：tan x/2=sin x/(1+cos x) 求证：1-sin(x)=cos(x)*tan(x/2) 求证tan^x-sin^2x=tan^2x*sin^2x 求证：(sin x+cos x)(1-tan x)=(2sin x)/(tan2x) 求证sin^4x-cos^4x=sin^2x-cos^2x 求证:(sin 2x /(1-cos 2x) )·(sin x /(1+sin x))=tan (π/4-x/2). 求证：cos2x=cos²x-sin²x 求证sin^4x+cos^4x=1-2sin^2xcos^2x 求证 sinˇ4X+sin²Xcos²X+cos²X = 1 求证 cos^8(x)-sin^8(x)=cos2x【1-1/2sin^2（2x)】 三角等式求证：cos^6x+sin^6x=1-3sin^2x+3sin^4x 求证（cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2x 请问下为什么sin3xsinx-cos3xcosx=cos4x? 求证:Sin^2 x / (sinx-cosx) - (sin x + cos x)/(ta求证:Sin^2 x / (sinx-cosx) - (sin x + cos x)/(tan^2-1) = sin x + cos x