Evaluate and simplify cos 2pi/3. The options for answers are in the picture attachment, but I have NO idea how to get any of them? Please, Any help is appreciated (:

Question

anonymous · Answer

attachment

terenzreignz · Answer

You again? :P
Ok, do you know what cos (pi/3) is? :D

anonymous · Answer

find the point corresponding to the angle  $\frac{2\pi}{3}$ on the unit circle 
use the attached cheat sheet. first coordinate is cosine, second coordinate is sine

saranya · Answer

cos(2Pi/3) = cos(120) = -1/2

anonymous · Answer

SO sorry! After I posted this my internet went wonky and I couldn't access this website ):

anonymous · Answer

@terenzreignz I know that cos pi/3 on a unit circle is 1/2, if that's what you mean (:

anonymous · Answer

You all were very helpful although I wasn't here to communicate about the problem (: