Вычислить[latex] \frac{2+5Sina*Cosa}{ Sin^{2}a-Sina*Cosa} [/latex]Если tga=0.5

[latex]\\\frac{sin\alpha}{cos\alpha}=\frac12 \\ \\sin\alpha=\frac12cos\alpha \\ \\sin^2\alpha+cos^2\alpha=1 \\ \\\frac14cos^2\alpha+cos^2\alpha=1 \\ \\cos^2\alpha=\frac45 \\ \\cos\alpha=\frac{2\sqrt5}{5} \\ \\sin\alpha=\frac{\sqrt5}{5} \\ \\\frac{2+5*\frac25}{\frac15-\frac25}=\frac{2+2}{-\frac15}=4*(-5)=-20[/latex]