cos\alpha=0,3
sin^2\alpha+cos^2\alpha=1
sin^2\alpha+(0,3)^2=1
sin^2\alpha=1-0,09
sin\alpha=\sqrt{0,91}
sin\alpha=\sqrt{\frac{91}{100}}
sin\alpha=\frac{\sqrt{91}}{10}
tg\alpha=\frac{sin\alpha}{cos\alpha}
tg\alpha=sin\alpha:cos\alpha
tg^2\alpha=(\frac{\sqrt{91}}{10}:\frac{3}{10})^2=(\frac{\sqrt{91}}{10}*\frac{10}{3})^2
tg^2\alpha=(\frac{\sqrt{91}}{3})^2=\frac{91}{9}=10\frac{1}{9}