SOLUTION: Find solutions in the internal (0,2π) Cos^2x+2cosx+1= 0 Sin2x+sinx=0

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Question 1072042: Find solutions in the internal (0,2π)
Cos^2x+2cosx+1= 0


Sin2x+sinx=0
Answer by ikleyn(52915) About Me  (Show Source):
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Find solutions in the internal (0,2π)
Cos^2x+2cosx+1= 0
~~~~~~~~~~~~~~~~~~~~~~~~ 

Cos%5E2%28x%29%2B2cos%28x%29%2B1 = 0  ====>  %28cos%28x%29%2B1%29%5E2 = 0  ====>  cos(x) + 1 = 0  ====>  

cos(x) = -1  ====>  x = pi.


Answer. There is only one solution in the given interval:  x = pi.

To see more examples of solved trigonometry equations with detailed solutions, look into the lessons
    - Solving simple problems on trigonometric equations
    - Solving typical problems on trigonometric equations
    - Solving more complicated problems on trigonometric equations
    - Solving advanced problems on trigonometric equations
in this site.


Also, you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Trigonometry: Solved problems".