Question 1059978
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*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \sec\varphi\ =\ \frac{1}{cos\varphi}]


So if


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \sec\theta\ =\ -2]


then


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


Use the unit circle.  The cosine of the angle between the positive *[tex \Large x]-axis and the terminal ray of the angle measured counterclockwise is the *[tex \Large x]-coordinate of the intersection of the terminal ray and the unit circle.


*[illustration unit_circle11_43203_lg.jpg].


By the way, avoid using the upper case form of theta (*[tex \Large \text{\Theta}]) since it has special meanings in both mathematics and science.  Use the lower case form (*[tex \Large \theta]) for a variable to represent an angle.


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">
*[tex \Large \ \
*[tex \LARGE \ \ \ \ \ \ \ \ \ \  

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