Question 627658
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Use the unit circle:


<img src="http://www.math.ucsd.edu/~jarmel/math4c/Unit_Circle_Angles.png">


And the following trigonometric identities:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \tan(\varphi)\ =\ \frac{\sin(\varphi)}{\cos(\varphi)}]


and 


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \sec(\varphi)\ =\ \frac{1}{\cos(\varphi)}]


Note that the *[tex \LARGE y]-coordinate of the point of intersection of the terminal ray of the angle *[tex \LARGE \theta] and the unit circle is the value of *[tex \LARGE \sin(\theta)], and the *[tex \LARGE x]-coordinate of the point of intersection of the terminal ray of the angle *[tex \LARGE \theta] and the unit circle is the value of *[tex \LARGE \cos(\theta)].


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