The following inequality is true for all x close to 0. \[2 – \frac{{{{\text{x}}^2}}}{3} < \frac{{{\text{x}}\sin {\text{x}}}}{{1 - \cos {\text{x}}}} < 2\] What is the value of \[\mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{{\text{x}}\sin {\text{x}}}}{{1 - \cos {\text{x}}}}?\] A. 1 B. 0 C. \[\frac{1}{2}\] D. 2

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The correct answer is $\boxed{\frac{1}{2}}$.

We can use the squeeze theorem to solve this problem. The squeeze theorem states that if $f(x) \leq g(x) \leq h(x)$ for all $x$ in a given interval, and $\lim_{x \to a} f(x) = \lim_{x \to a} h(x)$, then $\lim_{x \to a} g(x)$ also exists and is equal to the same value.

In this case, we have $2 – \frac{{{{\text{x}}^2}}}{3} < \frac{{{\text{x}}\sin {\text{x}}}}{{1 – \cos {\text{x}}}} < 2$ for all $x$ close to 0. We also know that $\lim_{x \to 0} 2 – \frac{{{{\text{x}}^2}}}{3} = 1$ and $\lim_{x \to 0} 2 = 2$. Therefore, by the squeeze theorem, we have $\lim_{x \to 0} \frac{{{\text{x}}\sin {\text{x}}}}{{1 – \cos {\text{x}}}} = \frac{1}{2}$.

We can also solve this problem by using L’Hôpital’s rule. L’Hôpital’s rule states that if $\lim_{x \to a} \frac{f(x)}{g(x)}$ exists and $\lim_{x \to a} \frac{f'(x)}{g'(x)}$ also exists, then $\lim_{x \to a} \frac{f(x)}{g(x)} = \lim_{x \to a} \frac{f'(x)}{g'(x)}$.

In this case, we have $\lim_{x \to 0} \frac{{{\text{x}}\sin {\text{x}}}}{{1 – \cos {\text{x}}}} = \lim_{x \to 0} \frac{{\text{x}} \cos {\text{x}} + \sin {\text{x}}}{-\sin {\text{x}}} = \lim_{x \to 0} \frac{{\text{x}} \cos {\text{x}} + \sin {\text{x}}}{-\sin {\text{x}}} = \frac{1}{2}$.

Therefore, the value of $\lim_{x \to 0} \frac{{{\text{x}}\sin {\text{x}}}}{{1 – \cos {\text{x}}}}$ is $\boxed{\frac{1}{2}}$.

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