Монгол Бодлогын Сан

$2\sin x=\sqrt{4+\cos 3x}\Leftrightarrow \left\{ % \begin{array}{l} \sin x\geq 0 \\ \cos x(4\cos^2x+\fbox{a}\cos x-\fbox{b})=0 \end{array}\right.\Leftrightarrow\\ \Leftrightarrow \left\{\begin{array}{l} \sin x\geq 0\\ \left[ % \begin{array}{l} \cos x=0 \\ \cos x=\dfrac{1}{\fbox{c}} \\ \end{array} % \right. \\ \end{array} % \right.$ $\Leftrightarrow$ $\left\{ % \begin{array}{l} \sin x\geq 0 \\ \left[ % \begin{array}{l} x=\dfrac{\pi}{\fbox{d}}+\fbox{e}k\pi \\ x=\pm\dfrac{\pi}{\fbox{f}}+\fbox{g}n\pi \\ \end{array} % \right. \\ \end{array} % \right.$ $\Leftrightarrow$ $\begin{array}{r}x=\dfrac{\pi}{2}+\fbox{h}k\pi, x=\dfrac{\pi}{\fbox{i}}+2n\pi,\\ k,n\in \mathbb Z.\end{array}$