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如果(1+ sin^4θ)sinθ>(1+ cos^4θ) cosθ,且θ大于0度小于360度,求θ的范围
注:那个是4次方
人气:185 ℃ 时间:2019-10-11 20:51:10
解答
(1+ sin^4θ)sinθ>(1+ cos^4θ) cosθ即sinθ+sin^5θ-cos^5θ-cosθ>0,也就是(sinθ-cosθ)+(sinθ-cosθ)(sin^4θ+sin^3θcosθ+sin^2θcos^2θ+sinθcos^3θ+cos^4θ)=(sinθ-cosθ)(1+sin^4θ+cos^4θ+sin^2...
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