SOLUTION: Find all solutions of the equation 2cos^2theta + cos2theta=0

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Question 437589: Find all solutions of the equation 2cos^2theta + cos2theta=0
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
2cos%5E2%28theta%29+%2B+cos%282theta%29+=+0
<==> 2cos%5E2%28theta%29+%2B+2cos%5E2%28theta%29+-+1+=+0
<==> 4cos%5E2%28theta%29+=+1
<==> cos%5E2%28theta%29+=+1%2F4
==> cos%28theta%29+=+-1%2F2, or cos%28theta%29+=+1%2F2
From the first equation, we get 240 degrees or 300 degrees.
From the 2nd equation we get 60 degrees or 120 degrees.
All solutions can described by the following:
60%5E0+%2B+n%2A180%5E0 or 120%5E0+%2B+n%2A180%5E0, where n varies over all the integers.