Question 937541
cos2x+3cosx+2=0 
2cos^2x - 1 + 3cosx + 2 = 0

2cos^2x + 3cosx + 1 = 0
(2cosx + 1)(cosx + 1) = 0
cosx = -1/2  0r cosx = -1
....
a)x=2pi/3 ,pi, 4pi/3
........

(cosx, sinx) Summary Unit Circle
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