0\\\cos\frac{3\pi}5tg\frac{\pi}9<0\\\\4\;u\;5\;-\;I\;\;4ETB.,\;sin\;u\;cos\;>0\\\sin4\cos5>0" alt="1.\;56^o=\frac{56}{180}\pi=\frac{14\pi}{45}\\170^o=\frac{170}{180}\pi=\frac{17\pi}{18}\\\\2.\;\frac{5\pi}6=\frac56\cdot180=5\cdot30=150^o\\2\frac16\pi=\frac{13}6\pi=\frac{13}6\cdot180=13\cdot30=390^o\\\\3.\;\frac{3\pi}5\;-\;II\;\;4ETB.,\;cos<0\\\frac\pi9\;-\;I\;\;4ETB.,\;tg>0\\\cos\frac{3\pi}5tg\frac{\pi}9<0\\\\4\;u\;5\;-\;I\;\;4ETB.,\;sin\;u\;cos\;>0\\\sin4\cos5>0" align="absmiddle" class="latex-formula">
0\\\sin\alpha=\frac7{25}\\tg\alpha=\frac{\sin\alpha}{\cos\alpha}=\frac7{25}:\left(-\frac{24}{25}\right)=-\frac7{25}\cdot\frac{25}{24}=-\frac7{24}\\\\5.\;tg420^o=tg(360^o+60^o)=tg60^o=\sqrt3\\3\cos\frac\pi2-2\sin\frac\pi6=0-2\cdot\frac12=-1" alt="4.\;\sin^2\alpha+\cos^2\alpha=1\Rightarrow\sin\alpha=\sqrt{1-\cos^2\alpha}=\sqrt{1-\frac{576}{625}}=\sqrt{\frac{49}{625}}=\pm\frac7{25}\\90^o<\alpha<180^o\Rightarrow\sin\alpha>0\\\sin\alpha=\frac7{25}\\tg\alpha=\frac{\sin\alpha}{\cos\alpha}=\frac7{25}:\left(-\frac{24}{25}\right)=-\frac7{25}\cdot\frac{25}{24}=-\frac7{24}\\\\5.\;tg420^o=tg(360^o+60^o)=tg60^o=\sqrt3\\3\cos\frac\pi2-2\sin\frac\pi6=0-2\cdot\frac12=-1" align="absmiddle" class="latex-formula">