Question 1104642
Find all solutions in the interval [0, 2π).

cos^2(x) + 2 cos x + 1 = 0
(cos(x) + 1)^2 = 0
cos(x) = -1
x = pi radians
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Find all solutions in the interval [0, 2π). 

(sin x)(cos x) = 0
sin(x) = 0
x = 0, pi
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cos(x) = 0
x = pi/2, 3pi/2