2sinα+3cosα=02sinα=-3cosαtanα=-3/2tan^2a=9/42sin平方α-3sinαcosα+1=-cos2α-3sinαcosα=sin^2α-cos^2α-3sinαcosα=(sin^2α-cos^2α-3sinαcosα)/(sin^2α+cos^2α)=(tan^2α-1-3tanα)/(tan^2α+1)...