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January 26, 2015

January 26, 2015

Posted by **Nikki** on Sunday, July 15, 2012 at 5:47pm.

- Trigonometry -
**Damon**, Sunday, July 15, 2012 at 5:49pmhuh?

cos 2 x = cos ( x+x )

= cos x cos x - sin x sin x

= cos^2 x - sin^2 x

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