SOLUTION: Solve for x on the interval [0,2pi]. cos^2(x)+3cos(x)+2=0 Someone please help, this assignment is due tomorrow and I cannot find how to do this anywhere.

Question 1043022: Solve for x on the interval [0,2pi].

cos^2(x)+3cos(x)+2=0

Someone please help, this assignment is due tomorrow and I cannot find how to do this anywhere.
Answer by ikleyn(52858) (Show Source): You can put this solution on YOUR website!
.

 = 


Factor left side

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


Then the original equation deploys in two separate independent equations

1.  cos(x) + 1 = 0  --->  cos(x) = -1  --->  x = ,  and


2.  cos(x) + 2 = 0  --->  cos(x) = -2,  which has no solutions.

Answer.  x = .

See the lessons in this site
    - Solving simple problems on trigonometric equations
    - Solving more complicated problems on trigonometric equations
    - Solving advanced problems on trigonometric equations

They teach you by examples on how to solve similar and other trigonometric equations.

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