已知tanα=-1/2,则（1+2sinαcosα）/(sin^2-cos^2)的值为_________._数学解答

已知tanα=-1/2,则（1+2sinαcosα）/(sin^2-cos^2)的值为_________.

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解答

（1+2sinαcosα）/(sin^2-cos^2)=(sin²a+cos²a+2sinacosa)/(sina-c0sa)(sina+cosa)=(sina+cosa)²/(sina-cosa)(sina+cosa)=(sina+cosa)/(sina-cosa)tana=-1/2分子分母同时除以cosa得=(tana+1)/(tana-...