Prove that lim sin(x)/x = 1 as x goes to 0(Epsilon delta )

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SUMMARY

The limit of the function \(\lim_{x\rightarrow 0} \frac{\sin x}{x} = 1\) is proven using the epsilon-delta definition of limits. Given any \(\epsilon > 0\), a corresponding \(\delta\) can be found such that \(\left|\frac{\sin x}{x} - 1\right| < \epsilon\) for \(|x| < \delta\). The proof utilizes the Taylor expansion of \(\sin(x)\) and establishes bounds on \(|x|\) to ensure that the limit holds true as \(x\) approaches zero.

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Amer
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Prove that

\lim_{x\rightarrow} \frac{\sin x}{x} = 1

Solution
Given \epsilon &gt; 0
want to find \delta such that \left|\frac{\sin x}{x} - 1 \right| &lt; \epsilon
for x, |x | &lt; \delta

can I use Taylor expansion of sinx ? but Taylor is an approximation of sin(x) around a certain point ? how to find such a delta ?
Thanks
 
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$$\left|\frac{\sin(x)}{x}-1\right| = \left|\frac{\sin(x)-x}{x}\right| = \frac{|\sin(x)-x|}{|x|} \leq \frac{|\sin(x)|+|x|}{|x|}$$

Note that $|\sin(x)|\leq 1$ therefore we can use the following upper bound
$$\frac{|\sin(x)|+|x|}{|x|}\leq \frac{1+|x|}{|x|}<\epsilon$$

At this point we can't to get rid of the $|x|$ in the denominator ($\epsilon$ can not be depending on $x$). We need another upper bound for $|x|$, note that $x$ has to lie in the neighbourhoud of $0$ thus it's allowed to say that $|x|<1$.

Can you make a conclusion now?
 
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