Question

How to solve this??

(2cos x + 1)(cos x + 1) = 0

Answer 1

(2cos x + 1)(cos x + 1) = 0(cos x + 1) = 0 means either
2cos x + 1= 0 or cos x + 1 = 0
can u solve nw?

Answer 2

since they are 2 factors, the easiest way would be to set the factors equal to zero:
2 cos x + 1 = 0 --> cos x =-1/2
cos x + 1 = 0 -> cos x = -1
Then take the inverse cosines, and you get
x = 120º (π/3) or x = 180º (π)