Đáp án:
Giải thích các bước giải:
$\begin{array}{l}
\mathop {\lim }\limits_{x \to {0^ + }} \frac{x}{{\sqrt {1 - \cos } }} = \mathop {\lim }\limits_{x \to {0^ + }} \frac{x}{{\sqrt {2{{\sin }^2}\frac{x}{2}} }}\\
= \mathop {\lim }\limits_{x \to {0^ + }} \frac{x}{{\sqrt 2 \,\left| {\sin \frac{x}{2}} \right|}} = \frac{1}{{\sqrt 2 }}\mathop {\lim }\limits_{x \to {0^ + }} \,\,\left( {\frac{x}{{2\sin \frac{x}{2}}}.2} \right) = \frac{1}{{\sqrt 2 }}.2 = \sqrt 2
\end{array}$
