若x=π/12,则cos^4x-sin^4x=

若x=π/12,则cos^4x-sin^4x= 根号下(sin""x+4cos"x)-根号下(cos""x+4sin"x)=? 证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4 求证（cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2 若x=π/12,则cos²x-sin²x的值等于 已知sin(π/2-x)+sin(π-x)/cos(-x)+sin(2π-x)=2009,则tan(x+5π/4)等于? sin^2x+cos^2x)(sin^4x-sin^2xcos^2x+cos^4x) =sin^4x-sin^2xcos 已知f(x)=cos^2x+sinxcosx g(x)=2sin(x+π/4)sin(x-π/4) 已知函数f(x)=cos^4 x－2sin x cos x－sin^4 x 若sin(π/2+x)=-4/5,x属于（π/2,π）,则cos(π/3-x)= sin（sin（sin（sin（x）=cos（cos（cos（cos（x）,X等于多少? 求证:sin(π/4+x)/sin(π/4-x)+cos(π/4+x)/(π/4-x)=2/cos2x