Differentiation

If \(\tan y=\frac{x \sin \alpha}{1-x \cos \alpha}\) and \(\frac{\mathrm{d} y}{\mathrm{~d} x}=\frac{\mathrm{m}}{x^2+2 \mathrm{n} x+1}\), then \(\mathrm{m}^2+\mathrm{n}^2\) is