A) \[\left\{ 2n\pi +\frac{\pi }{3}:n\in I \right\}\]
B) \[\left\{ n\pi \pm \frac{\pi }{6}:n\in I \right\}\]
C) \[\left\{ n\pi +\frac{\pi }{3}:n\in I \right\}\]
D) \[\left\{ 2n\pi -\frac{\pi }{3}:n\in I \right\}\]
Correct Answer: B
Solution :
We have \[\cos \,2x+2{{\cos }^{2}}\,x=2\Rightarrow \,2{{\cos }^{2}}\,x-1\,+2{{\cos }^{2}}\,x=2\]\[\Rightarrow \,\cos x=\pm \,\frac{\sqrt{3}}{2}\] \[\therefore \,\,x=n\pi \pm \,\frac{\pi }{6},\,\,\,n\in I\]
You need to login to perform this action.
You will be redirected in
3 sec
