[tex]\displaystyle tg\alpha=\frac{sen\alpha}{cos\alpha}\\\\\\\\tgx=\frac{senx}{cosx}\\\\\\tgx=\frac{\frac{3}{4}}{\frac{-\sqrt{7}}{4}}\\\\\\tgx=\frac{3}{4}.\frac{4}{-\sqrt{7}}\\\\tgx=\frac{3}{-\sqrt{7}}\\\\tgx=-\frac{3\sqrt{7}}{\sqrt{7}\sqrt{7}}\\\\tgx=-\frac{3\sqrt{7}}{7}[/tex]
