If $\cos 2\theta + 3\cos \theta = 0$, then the general value of $\theta $ is
$2n\pi \pm {\cos ^{ - 1}}\frac{{ - 3 + \sqrt {17} }}{4}$
$2n\pi \pm {\cos ^{ - 1}}\frac{{ - 3 - \sqrt {17} }}{4}$
$n\pi \pm {\cos ^{ - 1}}\frac{{ - 3 + \sqrt {17} }}{4}$
$n\pi \pm {\cos ^{ - 1}}\frac{{ - 3 - \sqrt {17} }}{4}$
Let $S={\theta \in\left(0, \frac{\pi}{2}\right): \sum_{m=1}^{9}}$
$\sec \left(\theta+(m-1) \frac{\pi}{6}\right) \sec \left(\theta+\frac{m \pi}{6}\right)=-\frac{8}{\sqrt{3}}$ Then.
The equation ${\sin ^4}x + {\cos ^4}x + \sin 2x + \alpha = 0$ is solvable for
Find the general solution of $\cos ec\, x=-2$
Find the principal and general solutions of the question $\tan x=\sqrt{3}$.
The number of solutions $x$ of the equation $\sin \left(x+x^2\right)-\sin \left(x^2\right)=\sin x$ in the interval $[2,3]$ is