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skr_girl · Mar 27, 2007, 04:58 AM

Yes me again - I have one more that is it!! I need to find out if the following is an identity or not:
_______
l cos2O = cosO

(that is square root cos squared theta equals cos theta)

Any help is really appreciated!!

Thanks
skr

Capuchin · Mar 27, 2007, 05:21 AM

$\sqrt{cos^2\theta} = cos\theta$

I don't know how you define an identity, but this equation is obviously true.

However I feel like it's too obvious to be an identity. All it really says is:

$cos^2\theta = (cos\theta)^2$

This is exactly what $cos^2\theta$ means.

I hope this helped a little bit but I'm not entirely sure what you are looking for :)

skr_girl · Mar 27, 2007, 06:24 AM

Thanks - I apologize this was not what I needed assistance on! I have been up for hours working on this and it is all starting to blend together! :-)~

Thank you so much!!

skr_girl · Mar 27, 2007, 07:51 AM

The identity I had to verify was:

Tanθ-cotμ = -2cotan2θ

Sorry for the mess up!! Thanks for all your help!