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