Question

Решите уравнение: cos2x+√2cosx+1/tgx-1=0

Answer 1

$\frac{Cos2x+\sqrt{2} Cosx+1}{tgx-1}=0\\\\\left \{ {{Cos2x+\sqrt{2}Cosx+1=0 } \atop {tgx-1\neq0 }} \right.\\\\\left \{ {{2Cos^{2}x-1+\sqrt{2}Cosx+1=0 } \atop {tgx\neq 1}} \right. \\\\\left \{ {{2Cos^{2}x+\sqrt{2}Cosx=0} \atop {x\neq\frac{\pi }{4}+\pi n,n\in Z}} \right.\\\\\sqrt{2} Cosx(\sqrt{2}Cosx+1)=0\\\\Cosx\neq 0\Rightarrow \sqrt{2}Cosx+1=0\\\\Cosx=-\frac{1}{\sqrt{2}}\\\\x=\pm arc Cos(-\frac{1}{\sqrt{2}})+2\pi n,n\in Z\\\\x=\pm \frac{3\pi }{4}+2\pi n,n\in Z$

$Otvet:\boxed{\pm \frac{3\pi }{4}+2\pi n,n\in Z}$