[tex]\alpha \in (0; 90)\\\\sin\alpha=0.8\\\\sin^2\alpha+cos^2\alpha=1\\0.8^2+cos^2\alpha=1\\0.64+cos^2\alpha=1 /-0.64\\cos^2\alpha=0.36\\cos\alpha=0.6\\\\tg\alpha=\frac{sin\alpha}{cos\alpha}\\tg\alpha=\frac{0.8}{0.6}=\frac4{5}*\frac{5}{3}=\frac43[/tex]
