[tex]Zad. 8\\\\4^2+x^2=10^2\\16+x^2=100\\x^2=100-16\\x^2=84\\x=\sqrt{4*21}=2\sqrt{21}\\\\cos\alpha=\frac{x}{10}=\frac{2\sqrt{21}}{50}=\frac{\sqrt{21}}5\\Odp. A[/tex]
[tex]Zad. 9\\P=(-3, -4)\\tg\alpha=\frac{y}x\\tg\alpha=\frac{-4}{-3}=\frac43\\\\Odp. C[/tex]
[tex]Zad. 10\\P=(-5, 12)\\cos\alpha=\frac{x}r\\r=|OP|\\r=\sqrt{(-5-0)^2+(12-0)^2}=\sqrt{(-5)^2+12^2}=\sqrt{25+144}=\sqrt{169}=13\\\\cos\alpha=\frac{-5}{13}=-\frac5{13}\\\\Odp. C[/tex]
