Sunday, 16 November 2014

calculus - Evaluate $lim_{xrightarrow 0} frac{sin x}{x + tan x} $ without L'Hopital



I need help finding the the following limit:




$$\lim_{x\rightarrow 0} \frac{\sin x}{x + \tan x} $$



I tried to simplify to:



$$ \lim_{x\rightarrow 0} \frac{\sin x \cos x}{x\cos x+\sin x} $$



but I don't know where to go from there. I think, at some point, you have to use the fact that $\lim_{x\rightarrow 0} \frac{\sin x}{x} = 1$. Any help would be appreciated.



Thanks!


Answer




$$
\frac{\sin x}{x + \tan x} = \frac{1}{\frac{x}{\sin x}+\frac{\tan x}{\sin x}} \to 1/2
$$


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