cos^2x/sin( π/4+x)cos(x+π/4),求① f(5π/12)

化简sin^4x-sin^2x+cos^2x 化简:sin^4 x-sin^2 x+cos^2 x 化简sin^4x+cos^2x 化简(sin^2x-cos^4x+cos^2x-sin^4x)/(sin^2x-cos^6x+cos^2x-sin^6x) 已知sin2x=(sinθ+cosθ)/2,cos^2x=sinθcosθ,那么cos2x的值是?2sin2x=sinθ+cosθ,平方得：4(sin2x)²=1+2 sinθcosθ,将cos²x=sinθcosθ代入得:4(sin2x)²=1+2cos²x,4(1- cos²2x) =1+2cos²x,4(1- cos²2x) =1+(1+co 求证:(sin 2x /(1-cos 2x) )·(sin x /(1+sin x))=tan (π/4-x/2). 化简sin(3π-x)cos(x-3/2)cos(4π-x)/tan(x-5π)cos(π/2+x)sin(x-5/2π) 化简sin(3π-x)cos(x-3/2)cos(4π-x)/tan(x-5π)cos(π/2+x)sin(x-5/2π) 化简1+sin x/cos x·sin2x/2cos²（π/4-x/2） 化简2sin^2[(π/4)+x]+根号3（sin^x-cos^x）-1 证明sin^4x-cos^4x=sin^2x-cos^2x 求证sin^4x-cos^4x=sin^2x-cos^2x 证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4 用cos x表示sin^4 x -sin^2 x +cos^2 x 用cos x表示sin^4x-sin^2 x+cos^2 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