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## anonymous one year ago I don't believe that I solved this problem correctly... (will post below)

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1. anonymous

$\frac{ \cos2\theta }{ \cos \theta -\sin \theta}$

2. anonymous

I know that $\cos2 \theta = 1-2\sin^2$ so I changed that to the numerator, and then plugged in my limit into the thetas, which is pi/4

3. anonymous

I ended up with 0/0 meaning that the limit didn't exist, but I have a feeling I did this wrong.

4. anonymous

Try the identity$\cos 2\theta = \cos^2\theta - \sin^2\theta$This can be factored and then the fraction can be simplified

5. anonymous

Let me clarify... pi/4 = c not the limit. Sorry about that.

6. Mertsj

$\frac{\cos ^2\theta-\sin ^2\theta}{\cos \theta-\sin \theta}=\frac{(\cos \theta-\sin \theta)(\cos \theta+\sin \theta)}{\cos \theta-\sin \theta}$

7. anonymous

Then I would just cancel out the like terms in the numerator and the denominator, plug in my c values and solve?

8. anonymous

That's right

9. anonymous

Oh okay, thank you. :) I guess I'll medal ospreytriple since they responded first? But I'll fan both of you. :)

10. anonymous

not to butt in but if you get $\frac{0}{0}$ it does NOT mean the limit doesn't exist it means you have to do more work

11. anonymous

Great to know! I'll keep that in mind next time I get it as an answer.

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