Ответ:

[tex]sin\alpha=\frac{3}{5}\\\\tg\alpha= \frac{ 3 }{ 4 }[/tex]

Объяснение:

[tex]sin^2\alpha+cos^2\alpha=1\\\\ sin^2\alpha+\left( \frac{ 4 }{ 5 } \right) ^2=1\\\\ sin^2\alpha + \frac{ 16 }{ 25 } =1\\\\ sin^2\alpha=1- \frac{ 16 }{ 25 } \\\\ sin^2\alpha= \frac{ 9 }{ 25 } \\\\ sin\alpha=\sqrt \frac{ 9 }{ 25 } \\\\ sin\alpha= \frac{3}{5}[/tex]

[tex]tg\alpha=\frac{sin\alpha}{cos\alpha}\\\\ tg\alpha=\frac{\frac{3}{5}}{ \frac{ 4 }{ 5 } }\\\\tg\alpha= \frac{3}{5}\cdot\frac{5}{4}\\\\tg\alpha= \frac{ 3 }{ 4 }[/tex]