(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

[itex]\stackrel{lim}{x\rightarrow 0}\frac{cos^2x-1}{2xsinx}[/itex]

2. Relevant equations

[itex]\stackrel{lim}{x\rightarrow 0}\frac{1-cosx}{x}=0[/itex]

[itex]\stackrel{lim}{x\rightarrow 0}\frac{sinx}{x}=1[/itex]

3. The attempt at a solution

I found this problem online (and can't remember where). It was in a limits section, so it can be solved without using l'Hopitals rule. I gave it to my class today, and then we all got stuck. We know the answer is -.5 but can't get it algebraically. Any advice?

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# Homework Help: Finding a Trig Limit by hand, no L'Hopitals!

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