Question 672290
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Use the unit circle (or your memory) to find *[tex \LARGE \cos^{-}\left(\frac{7\pi}{4}\right)] and *[tex \LARGE \sin^{-1}\left(\frac{7\pi}{4}\right)]


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


Hint:  Remember that cosine is the *[tex \LARGE x]-coordinate and sine is the *[tex \LARGE y] coordinate on the unit circle.


From *[tex \LARGE a\ =\ r\cos(\theta)] and *[tex \LARGE b\ =\ r\sin(\theta)], we get, for this problem:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \frac{a}{8}\ =\ \frac{\sqrt{2}}{2}]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \frac{b}{8}\ =\ -\frac{\sqrt{2}}{2}]



The rest is just arithmetic.


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