trig
posted by Anonymous .
I'm confused with this concept:
Okay, so I have this problem:
cos2x( 2 cos+1)= 0
I understand I have to work the problems separately and I get cos x= 2 and cos x= 1/2
Now, what I don't understand is how this connects to pi, radians or the unit circle. If someone could explain or point me to a place with a thorough explanation, please tell me. B/c trust me, I've looked EVERYWHERE and my book/teacher doesn't really explain the theory very well.

I get cos x= 2 ?????
I do not
I get
cos 2 x = 0
that means that 2x = pi/2 or 90 degrees or 2x = 3 pi/2 or 270 degrees
or x = pi/4 or 3pi/4
then
cos x = 1/2
well cos of 60 degrees or pi/3 is 1/2
so cos (18060) = 1/2 so x =2pi/3
or 180+60 which is 5pi/3 
sry it's cos^2x