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December 19, 2014

December 19, 2014

Posted by **Josh** on Thursday, February 23, 2012 at 9:46pm.

Ive got the equation down to -cos^2(x)+cos(x)+1=0 or and it can be simplified too sin^2(x)+cos(x)=0

If you could tell me where to go from either of these two, it would be great help.. Thankyou for any responses

- Precalculus -
**Steve**, Friday, February 24, 2012 at 10:40amcos^2(x) + cos(x) = 2cos^2(x) - 1

cos^2(x) - cos(x) - 1 = 0

This is just like

u^2 - u - 1 = 0

u = [1 +/- sqrt(5)]/2

since u = cos(x) and must be less than 1,

cos(x) = (1-sqrt(5))/2

will be in QII or QIII

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