求证1+2sina cosa/sin^2a-cos^2a=tana+1/tana-1

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求证1+2sinacosa/sin^2a-cos^2a=tana+1/tana-1求证1+2sinacosa/sin^2a-cos^2a=tana+1/tana-1求证1+2sinacosa/sin^

求证1+2sina cosa/sin^2a-cos^2a=tana+1/tana-1
求证1+2sina cosa/sin^2a-cos^2a=tana+1/tana-1

求证1+2sina cosa/sin^2a-cos^2a=tana+1/tana-1
(1+2sinacosa)/[(sina)^2-(cosa)^2]
=(sina+cosa)^2/[(sina+cosa)(sina-cosa)]
=(sina+cosa)/(sina-cosa) 分子分母同除cosa
=(tana+1)/(tana-1)