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December 9, 2016
Posted by **Anonymous** on Monday, December 5, 2011 at 6:17pm.

- mathematics -
**Steve**, Tuesday, December 6, 2011 at 12:03am4 sin^2 = 1 - 2cos + cos^2

4 - 4 cos^2 = 1 - 2cos + cos^2

5cos^2 - 2cos - 3 = 0

cosx = 1 or -.6

x = 0 or 126.86°