$$\lim_{x \to 0^-} \sqrt{\cos{\left(2 x \right)}} = 1$$
More at x→0 from the left$$\lim_{x \to 0^+} \sqrt{\cos{\left(2 x \right)}} = 1$$
$$\lim_{x \to \infty} \sqrt{\cos{\left(2 x \right)}} = \left\langle 0, 1\right\rangle$$
More at x→oo$$\lim_{x \to 1^-} \sqrt{\cos{\left(2 x \right)}} = \sqrt{\cos{\left(2 \right)}}$$
More at x→1 from the left$$\lim_{x \to 1^+} \sqrt{\cos{\left(2 x \right)}} = \sqrt{\cos{\left(2 \right)}}$$
More at x→1 from the right$$\lim_{x \to -\infty} \sqrt{\cos{\left(2 x \right)}} = \left\langle 0, 1\right\rangle$$
More at x→-oo