sin(60-x)=1/4,cos(60+2x)=

求证（cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2x sin(60-x)=1/4,cos(60+2x)= 证明一个sin&cos的等式证明 1+sin^2(x)+sin^4(x)+sin^6(x)=[1-sin^8(x)]/[cos^2(x)] 求证(3-sin^4 x-cos^4 x)/2cos^2 x=1+tan^2 x+sin^2 x cos(2x+60`)cos(x-30`)+sin(2x+60`)sin(x-30`)=1/2求这题的题解...60` 是60度. (1+cos x-sin x)/(1-sin x-cos x)+(1-cos x-sin x)/(1-sin x+cos x)=? 若cos (x+30°)+sin x =4/5,则cos (2x-60°)等于? 求证（cos^2x-sin^2x)(cos^4x+sin^4x）+1/4sin2xsin4x=cos2x (1-cos^4X-sin^4x)∕(1-cos^6x-sin^6x)=化简(急) 求证：1-cos^4x-sin^4x/1-cos^6x-sin^6x=2/3 证明1-sin^6x-cos^2x/1-sin^4x-cos^4x=3/2 一道三角函数证明题sin^4 X+cos^4 X=1-2sin^2 X cos^2 X sin（sin（sin（sin（x）=cos（cos（cos（cos（x）,X等于多少? 求证:(sin 2x /(1-cos 2x) )·(sin x /(1+sin x))=tan (π/4-x/2). 已知sin[a-b]cos a-cos[b-a]sin a=3/5,b是第三象限角,求sin[b+5π/4]的值第一题1/2cos x-√3/2sin x第二题√3sin x+cos x第三题√2[sin x-cos x]第四题√2cos x-√6sin x 若sinx+sin^2x=1,则cos^2x+cos^4x=? cos 2x(1-2sin^2 2x) + cos 4x (1+cos 2x)= 求证sin^4x+cos^4x=1-2sin^2xcos^2x