Question

решить неравенство √(1+2cos(x))>sin(x)

Answer 1

$\sqrt{1+2cosx}sinx\ \ \Leftrightarrow \ \ \ \left[\begin{array}{l}\left\{\begin{array}{l}sinx\geq 0\\1+2cosxsin^2x\end{array}\right\\\\\left\{\begin{array}{l}sinxsin^2x\end{array}\right\ \ \left\{\begin{array}{l}2\pi n\leq x\leq \pi +2\pi n\ ,\ n\in Z\\1-sin^2x+2cosx0\end{array}\right$

$\left\{\begin{array}{l}2\pi n\leq x\leq \pi +2\pi n\ ,\ n\in Z\\cos^2x+2cosx0\end{array}\right\ \ \left\{\begin{array}{l}2\pi n\leq x\leq \pi +2\pi n\ ,\ n\in Z\\cosx\, (cosx+2)0\end{array}\right$

$\left\{\begin{array}{l}2\pi n\leq x\leq \pi +2\pi n\ ,\ n\in Z\\cosx0\end{array}\right\ \ \left\{\begin{array}{l}2\pi n\leq x\leq \pi +2\pi n\ ,\ n\in Z\\-\dfrac{\pi}{2}+2\pi k$

$b)\ \ \left\{\begin{array}{l}sinx$

$\left\{\begin{array}{l}-\pi +2\pi n\$

$Otvet:\ \ x\in \Big[-\dfrac{2\pi }{3}+2\pi n\ ;\ \dfrac{\pi}{2}+2\pi n\ \Big)\ ,\ n\in Z$