![\displaystyle \frac{6 cos^2x-5 \sqrt{2} cosx+2}{lg(tgx)}=0](https://tex.z-dn.net/?f=%5Cdisplaystyle++%5Cfrac%7B6+cos%5E2x-5+%5Csqrt%7B2%7D+cosx%2B2%7D%7Blg%28tgx%29%7D%3D0+)
![\displaystyle ODZ:\\\\ \left \{ {{lg(tgx) \neq 0} \atop {tgx\ \textgreater \ 0}} \right. \\\\ \left \{ {{tgx \neq 1} \atop {x\in ( \pi n; \frac{ \pi }{2}+ \pi n) n\in Z}} \right. \\\\ \left \{ {{x \neq \frac{ \pi }{4}+ \pi n; n\in Z} \atop {x\in ( \pi n; \frac{ \pi }{2}+ \pi n); n\in Z}} \right.](https://tex.z-dn.net/?f=%5Cdisplaystyle+ODZ%3A%5C%5C%5C%5C+%5Cleft+%5C%7B+%7B%7Blg%28tgx%29+%5Cneq+0%7D+%5Catop+%7Btgx%5C+%5Ctextgreater+%5C+0%7D%7D+%5Cright.+%5C%5C%5C%5C+%5Cleft+%5C%7B+%7B%7Btgx+%5Cneq+1%7D+%5Catop+%7Bx%5Cin+%28+%5Cpi+n%3B++%5Cfrac%7B+%5Cpi+%7D%7B2%7D%2B+%5Cpi+n%29+n%5Cin+Z%7D%7D+%5Cright.+%5C%5C%5C%5C+%5Cleft+%5C%7B+%7B%7Bx+%5Cneq++%5Cfrac%7B+%5Cpi+%7D%7B4%7D%2B+%5Cpi+n%3B+n%5Cin+Z%7D+%5Catop+%7Bx%5Cin+%28+%5Cpi+n%3B++%5Cfrac%7B+%5Cpi+%7D%7B2%7D%2B+%5Cpi+n%29%3B+n%5Cin+Z%7D%7D+%5Cright.+)
дробь равна нулю когда числитель равен нулю
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![\displaystyle cosx= \frac{ \sqrt{2}}{2}\\\\x_{1.2}=\pm \frac{ \pi }{4}+2 \pi n; n\in Z\\\\x_1= \frac{ \pi }{4}+2 \pi n; n\in Z](https://tex.z-dn.net/?f=%5Cdisplaystyle+cosx%3D++%5Cfrac%7B+%5Csqrt%7B2%7D%7D%7B2%7D%5C%5C%5C%5Cx_%7B1.2%7D%3D%5Cpm++%5Cfrac%7B+%5Cpi+%7D%7B4%7D%2B2+%5Cpi+n%3B+n%5Cin+Z%5C%5C%5C%5Cx_1%3D+%5Cfrac%7B+%5Cpi+%7D%7B4%7D%2B2+%5Cpi+n%3B+n%5Cin+Z+++++)
не входит в ОДЗ
![\displaystyle x_2=- \frac{ \pi }{4}+2 \pi n; n\in z](https://tex.z-dn.net/?f=%5Cdisplaystyle+x_2%3D-+%5Cfrac%7B+%5Cpi+%7D%7B4%7D%2B2+%5Cpi+n%3B+n%5Cin+z+)
не входит в ОДЗ
![\displaystyle cosx= \frac{ \sqrt{2}}{3}\\\\x_{3.4}=\pm arccos( \frac{ \sqrt{2}}{3})+2 \pi n; n\in Z\\\\x_3=- arccos( \frac{ \sqrt{2}}{3})+2 \pi n; n\in Z](https://tex.z-dn.net/?f=%5Cdisplaystyle+cosx%3D+%5Cfrac%7B+%5Csqrt%7B2%7D%7D%7B3%7D%5C%5C%5C%5Cx_%7B3.4%7D%3D%5Cpm+arccos%28+%5Cfrac%7B+%5Csqrt%7B2%7D%7D%7B3%7D%29%2B2+%5Cpi+n%3B+n%5Cin+Z%5C%5C%5C%5Cx_3%3D-+arccos%28+%5Cfrac%7B+%5Csqrt%7B2%7D%7D%7B3%7D%29%2B2+%5Cpi+n%3B+n%5Cin+Z+++)
не входит в ОДЗ
ОТВЕТ
![\displaystyle x_4=arccos \frac{ \sqrt{2}}{3}+2 \pi n; n\in Z](https://tex.z-dn.net/?f=%5Cdisplaystyle+x_4%3Darccos++%5Cfrac%7B+%5Csqrt%7B2%7D%7D%7B3%7D%2B2+%5Cpi+n%3B+n%5Cin+Z+)
Знак V корень квадратный
5/7 • V 147 • V 3 = 5/7 • ( V ( 147 • 3 )) = 5/7 • V 441 = 5/7 • 21 = 5 • 3 = 21
Ответ:
Объяснение:преобразуем выражение в знаменателе дроби:
(sin11°·sin46°·sin68°·sin79°)²=(sin11°·sin(90°-11°)·sin46°·sin68°)²=
(sin11°·cos11°·sin(90-44°)·sin(90-22°)²=(1/2·2sin11°·cos11°·cos44°·cos22°)²=
(1/2·sin22°·cos22°·cos44°)²=(1/4·2sin22°·cos22°·cos44°)²=(1/4sin44°·cos44°)²=(1/8·2sin44°·cos44°)²=(1/8sin88°)²=1/64sin²88°.
имеем, 3sin²88° / (1/64·sin²88°)=3·64=192.
(применяем формулы 2sinα·cosα=sin2α, и формулы дополнительного угла sin79=cos11,sin46=cos44° или формулы приведения)
25% от 18000 это 18000 :100 * 25 = 180 *25 = 4500
В 1 уверена точно, второй, простите, не знаю, на счет 3 тоже не уверена, но по сути должно быть так.