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Решите задачу:

$\frac{Cos\alpha -2Sin\alpha }{Sin\alpha+Cos\alpha}-\frac{2-Cos^{2}\alpha}{Cos^{2}\alpha-Sin^{2}\alpha}=\frac{(Cos\alpha-2Sin\alpha)*(Cos\alpha-Sin\alpha)-2+Cos^{2}\alpha}{Cos^{2}\alpha-Sin^{2}\alpha}}=$ $\frac{Cos^{2}\alpha-Sin\alpha Cos\alpha-2Sin\alpha Cos\alpha+2Sin^{2}\alpha-2+Cos^{2} \alpha}{Cos^{2}\alpha-Sin^{2}\alpha}=\frac{2Sin^{2}\alpha+2Cos^{2} \alpha-2-3Sin\alpha Cos\alpha}{Cos2\alpha }=-\frac{3Sin\alpha Cos\alpha}{Cos2\alpha}=-\frac{1,5Sin2\alpha }{Cos2\alpha }=-1,5tg2\alpha$