Q. $\left\{ x \in R:\cos{2x + 2\cos^{2}{x = 2}} \right\}$ is equal to
A) $\left\{ 2n\pi + \frac{\pi}{3}:n \in Z \right\}$
B) $\left\{ n\pi \pm \frac{\pi}{6}:n \in Z \right\}$
C) $\left\{ n\pi + \frac{\pi}{3}:n \in Z \right\}$
D) $\left\{ 2n\pi - \frac{\pi}{3}:n \in Z \right\}$
Explanation
(b)
Given, $2\cos^{2}{x - 1 + 2\cos^{2}{x = 2}}$
$\Rightarrow \ \ \ \cos{x = \pm \frac{\sqrt{3}}{2}}\ \ \ \ \therefore x = n\pi \pm \frac{\pi}{6}\ :n \in Z$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.