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December 18, 2014

December 18, 2014

Posted by **sandeep** on Friday, August 17, 2012 at 10:16am.

- math -
**Steve**, Friday, August 17, 2012 at 2:54pmdropping the x's for brevity,

2cos^2 - 1 = 2sin cos

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

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

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

8cos^4 - 8cos^2 + 1 = 0

cos^2 = 1/4 (2 ± √2)

x = kπ/2 ± π/8 for integer k

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