化简1/4sin2x*sin4x-sin^8x+cos^8x
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化简1/4sin2x*sin4x-sin^8x+cos^8x
化简1/4sin2x*sin4x-sin^8x+cos^8x
化简1/4sin2x*sin4x-sin^8x+cos^8x
1/4sin2x*sin4x-sin^8x+cos^8x
=sinxcosxsin2xcos2x+(cos^4x+sin^4x)(cos^4x-sin^x)
=2sin^2xcos^2xcos2x+(cos^4x+sin^4x)(cos^2x-sin^2x)
=cos2x(sin^2x+cos^2x)^2
=cos2x