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February 28, 2015

February 28, 2015

Posted by **Johnathan** on Thursday, May 1, 2008 at 4:18pm.

cos(pi/12)

- trig -
**Reiny**, Thursday, May 1, 2008 at 4:22pmHint #1 : pi/12 = 1/2 of pi/6, and you should be familiar with the trig ratios of pi/6 or 30º

Hint #2 : cos 2A = 2cos^2 A - 1

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