2(sin^6 α +cos^6α)-3(sin^4a+cos^4α)
问题描述：
2(sin^6 α +cos^6α)-3(sin^4a+cos^4α)
答
sin^6α +cos^6α=(sin^2α+cos^2α)(sin^4α-sin^2αcos^2α+cos^4α)=sin^4α-sin^2αcos^2α+cos^4α2(sin^6 α +cos^6α)-3(sin^4α+cos^4α)=2sin^4α-2sin^2αcos^2α+2cos^4α-3sin^4α-3cos^4α=-sin^4α-co...