（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...