SOLUTION: I tried this several times. But unable to factor. question is -- Solve 2cos^3theta+2costheta-costheta-1=0 for theta lying between 0 and 360 degrees

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Question 1140882: I tried this several times. But unable to factor.
question is --
Solve
2cos^3theta+2costheta-costheta-1=0
for theta lying between 0 and 360 degrees
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
If this is 2 cos^3 theta+2 cos^2 theta-cos theta-1=0
(which makes sense, because otherwise you could combine the second and third terms)
then it factors into (2cos^2 theta-1) (cos theta+1)=0
and theta =+/- sqrt(2)/2 (45, 135 225, 315 deg)
and -1 (180 degrees)