Question 890281
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*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \theta\ +\ 2k\pi\ =\ \theta\,\forall\,k\ \in\ \mathbb{Z}]


But


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \frac{9\pi}{2}\ =\ 4\pi\ +\ \frac{\pi}{2}\ =\ 2(2)\pi\ +\ \frac{\pi}{2}\ =\ \frac{\pi}{2}].


Use the unit circle to find *[tex \Large \sin\left(\frac{\pi}{2}\right)] and *[tex \Large \cos\left(\frac{\pi}{2}\right)].


Then use:


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


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \cos\varphi\ =\ \frac{1}{\tan\varphi}]


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


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \csc\varphi\ =\ \frac{1}{\sin\varphi}]


Note:  Some of these functions will be undefined at *[tex \Large \frac{\pi}{2}]


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