SOLUTION: Find all solutions of each equation in the interval [0,2π) cos(2x) + cos(x) = 2

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Question 1155026: Find all solutions of each equation in the interval [0,2π)
cos(2x) + cos(x) = 2
Answer by ikleyn(52890) About Me  (Show Source):
You can put this solution on YOUR website!
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Good student should see the solution to this problem MOMENTARILY. 

    The function cosine is NEVER greater than 1.


    Hence, the sum of two cosine functions can be equal to 2 if and only if each addend is equal to 1.



    ANSWER.  In the given interval, the equation has a unique solution x = 0.