赞 love_destiny 幼苗
共回答了19个问题采纳率：100% 举报
sin^6x+cos^6x
=(sin^2x+cos^2x)(sin^4x-sin^2xcos^2x+cos^4x)
=sin^4x-sin^2xcos^2x+cos^4x
=(sin^2x+cos^2x)^2-3sin^2xcos^2x
=1-3sin^2xcos^2x
所以分子=3sin^2xcos^2x
sin^4x+cos^4x
=(sin^2x+cos^2x)^2-2sin^2xcos^2x
=1-2sin^2xcos^2x
所以分母=2sin^2xcos^2x
所以原式=3/2
=(sin^2x+cos^2x)(sin^4x-sin^2xcos^2x+cos^4x)
=sin^4x-sin^2xcos^2x+cos^4x
=(sin^2x+cos^2x)^2-3sin^2xcos^2x
=1-3sin^2xcos^2x
所以分子=3sin^2xcos^2x
sin^4x+cos^4x
=(sin^2x+cos^2x)^2-2sin^2xcos^2x
=1-2sin^2xcos^2x
所以分母=2sin^2xcos^2x
所以原式=3/2
1年前
7
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