Question 1120994
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*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2\cos^2(x)\ +\ \cos(x)\ =\ 0]


Let *[tex \Large u\ =\ \cos(x)]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2u^2\ +\ u\ =\ 0]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ u(2u\ +\ 1)\ =\ 0]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ u\ =\ 0]


or


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ u\ =\ -\frac{1}{2}]


So


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \cos(x)\ =\ 0]


or


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \cos(x)\ =\ -\frac{1}{2}]


Use the unit circle to find all of the angles where *[tex \Large \cos(x)\ =\ 0] or *[tex \Large \cos(x)\ =\ -\frac{1}{2}]
								
								
John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it
<img src="http://c0rk.blogs.com/gr0undzer0/darwin-fish.jpg">
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*[tex \LARGE \ \ \ \ \ \ \ \ \ \  
								
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