分子化简下，4cos^4x-2cos2x-1=（2cosx＾2）＾2-2cos2x-1=(1+cos2x)＾2-2cos2x-1=cos2x＾2
分母其实不化简也行，直接代入都可以算了，tan（π/4+x)=tan(3π/12-17π/12)=tan(-7π/6)=tan(5π/6)=-tan(π/6)=-√3/3，sin^2(π/4-x)]=sin^2(π/4+17π/12)=sin^2...
已知函数f(x)=(4cos^4x-2cos2x-1)/[tan（π/4+x)sin^2(π/4-x)] 求f(-17π
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已知函数f(x)=(4cos^4x-2cos2x-1)/[tan（π/4+x)sin^2(π/4-x)] 求f(-17π
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