化简1/4sin2x*sin4x-sin^8x+cos^8x
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![化简1/4sin2x*sin4x-sin^8x+cos^8x](/uploads/image/z/8862824-56-4.jpg?t=%E5%8C%96%E7%AE%801%2F4sin2x%2Asin4x-sin%5E8x%2Bcos%5E8x)
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