Question 768031
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Find the two points on the unit circle illustrated where the *[tex \LARGE y]-coordinate is equal to *[tex \LARGE -\frac{\sqrt{3}}{2}].


<img src="http://prec.alcul.us/wp-content/uploads/unitcircle.gif">


Now, *[tex \LARGE x] has to be in the interval [*[tex \LARGE 0,2\pi]), but that means *[tex \LARGE 2x] is in the interval [*[tex \LARGE 0,4\pi]).   Hence the two points you found on the circle are actually 4 possibilities for the value of *[tex \LARGE 2x], namely *[tex \LARGE \frac{4\pi}{3},\,\frac{5\pi}{3},\,\frac{10\pi}{3},\,\frac{11\pi}{3}].  Divide each possibility for *[tex \LARGE 2x] by 2, and you will have 4 numbers that match one of your answer choices.


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
<font face="Math1" size="+2">Egw to Beta kai to Sigma</font>
My calculator said it, I believe it, that settles it
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