1-(sin^6x+cos^6x)=3sin^2xcos^2x 如何证明?
问题描述：
1-(sin^6x+cos^6x)=3sin^2xcos^2x 如何证明?
答
1-(sin^6x+cos^6x)=3sin^2xcos^2x 只要证明sin^6x+cos^6x=1-3sin^2xcos^2x sin^6x +cos^6x =(sin^2x +cos^2x)(sin^4x -sin^2xcos^2x +cos^4x) =(1)(sin^4x +2cos^2xsin^2x +cos^4x -2sin^2xcos^2x -sin^2xcos^2x)=(s...