Question

З 7 по 12 на листочку

Answer 1

$\displaystyle\bf\\7)\\\\tg2,1\pi =tg\Big(2\pi +\frac{\pi }{10} \Big)=tg\frac{\pi }{10} \\\\8)\\\\Ctg\frac{15\pi }{7} =Ctg\Big(2\pi +\frac{\pi }{7} \Big)=Ctg\frac{\pi }{7} \\\\9)\\\\Cos1325^{0} =Cos(8\pi -115^{0} )=Cos115^{0} =\\\\=Cos(90^{0} +25^{0})=-Sin25^{0} \\\\10)\\\\tg2000^{0}=tg(10\pi +200^{0} )=tg200^{0}=\\\\=tg(180^{0}+20^{0})= tg20^{0} \\\\11)$

$\displaystyle\bf\\Sin6,3\pi =Sin\Big(6\pi +\frac{3}{10} \pi \Big)=Sin\frac{3}{10} \pi =\\\\=Sin\Big(\frac{\pi }{2} -\frac{2\pi }{10} \Big)=Cos\frac{\pi }{5} \\\\12)\\\\Cos\frac{27\pi }{8} =Cos\Big(4\pi -\frac{5\pi }{8}\Big)=Cos\frac{5\pi }{8} =\\\\=Cos\Big(\frac{\pi }{2} +\frac{\pi }{8} \Big)=-Sin\frac{\pi }{8}$