Question 1018145
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*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \sec\varphi\ =\ \frac{1}{\cos\varphi}]


so


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \frac{1}{\cos\theta}\ =\ \frac{2\sqrt{3}}{3}\ =\ \frac{2}{\sqrt{3}}]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \cos\theta\ =\ \frac{\sqrt{3}}{2}]


Note: The value of cosine is the value of the *[tex \Large x]-coordinate of the intersection of the terminal ray of an angle and the unit circle.  Note that there are two points with the desired *[tex \Large x]-coordinate.  Multiply radians by *[tex \Large \frac{180}{\pi}] to get degrees.


 *[illustration unit_circle11_43203_lg.jpg].


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it

*[tex \Large \ \
*[tex \LARGE \ \ \ \ \ \ \ \ \ \  

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