![cosx\ \textgreater \ 0\\ - \frac{ \pi }{2} +2 \pi n\ \textless \ x\ \textless \ \frac{ \pi }{2} +2 \p \pi i n\\ tg^2+tgx=0\\ tgx(tgx+1)=0\\[tex] - \frac{7 \pi }{2} \leq- \frac{ \pi }{4} +2 \pi k \leq -2 \pi |+ \frac{ \pi }{4} \\ - \frac{14\pi }{4} + \frac{\pi}{4} \leq2 \pi k \leq - \frac{8 \pi }{4} + \frac{ \pi }{4}\ |: 2\pi \\ - \frac{13}{8} \leq k \leq - \frac{7}{8} , \ k=-1, \ x=-2 \pi](https://tex.z-dn.net/?f=cosx%5C+%5Ctextgreater+%5C+0%5C%5C+-+%5Cfrac%7B+%5Cpi+%7D%7B2%7D+%2B2++%5Cpi+n%5C+%5Ctextless+%5C+x%5C+%5Ctextless+%5C++%5Cfrac%7B+%5Cpi+%7D%7B2%7D+%2B2+%5Cp+%5Cpi+i+n%5C%5C+tg%5E2%2Btgx%3D0%5C%5C+tgx%28tgx%2B1%29%3D0%5C%5C%5Btex%5D+-+%5Cfrac%7B7+%5Cpi++%7D%7B2%7D+%5Cleq-+%5Cfrac%7B+%5Cpi+%7D%7B4%7D+%2B2+%5Cpi+k+%5Cleq+-2+%5Cpi+%7C%2B+%5Cfrac%7B+%5Cpi+%7D%7B4%7D+%5C%5C+-+%5Cfrac%7B14%5Cpi+%7D%7B4%7D+%2B+%5Cfrac%7B%5Cpi%7D%7B4%7D+%5Cleq2+%5Cpi+k+%5Cleq+-++%5Cfrac%7B8+%5Cpi+%7D%7B4%7D+%2B+%5Cfrac%7B+%5Cpi+%7D%7B4%7D%5C+%7C%3A+2%5Cpi+%5C%5C+-+%5Cfrac%7B13%7D%7B8%7D+%5Cleq+k+%5Cleq+-+%5Cfrac%7B7%7D%7B8%7D+%2C+%5C+k%3D-1%2C+%5C+x%3D-2+%5Cpi+ "cosx\ \textgreater \ 0\\ - \frac{ \pi }{2} +2 \pi n\ \textless \ x\ \textless \ \frac{ \pi }{2} +2 \p \pi i n\\ tg^2+tgx=0\\ tgx(tgx+1)=0\\[tex] - \frac{7 \pi }{2} \leq- \frac{ \pi }{4} +2 \pi k \leq -2 \pi |+ \frac{ \pi }{4} \\ - \frac{14\pi }{4} + \frac{\pi}{4} \leq2 \pi k \leq - \frac{8 \pi }{4} + \frac{ \pi }{4}\ |: 2\pi \\ - \frac{13}{8} \leq k \leq - \frac{7}{8} , \ k=-1, \ x=-2 \pi")
tgx=0, \ x= \pi n, \ uchitivaya\ ODZ:\ x=2 \pi n\\
tgx=-1, \ x=- \frac{ \pi }{4} + \pi k, \ uchitivaya \ ODZ: \ x=- \frac{ \pi }{4}+2 \pi k\\
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2) \ - \frac{7 \pi }{2} \leq 2\pi n \leq -2 \pi |:2\pi \\
- \frac{7}{4} \leq n \leq -1, \ n=-1, \ x=-2\\
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