$\cos \theta=\frac{1}{\sqrt{2}}$ হলে $\theta=$ কত?

$2 \mathrm{n} \pi+\frac{\pi}{4}, \mathrm{n} \in \mathbb{Z}$

$2 n \pi \pm \frac{\pi}{4}, n \in \mathbb{Z}$

$2 n \pi-\frac{\pi}{4}, n \in \mathbb{Z}$

$2 n \pi+(-1)^{n} \frac{\pi}{3} ; n \in \mathbb{Z}$