SOLUTION: 2cos2 ∅-2√2cos∅+1=0

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Question 1120627: 2cos2 ∅-2√2cos∅+1=0
Answer by greenestamps(13209) About Me  (Show Source):
You can put this solution on YOUR website!


The expression is a perfect square trinomial....

2%28cos%28x%29%29%5E2-%282%2Asqrt%282%29%29%28cos%28x%29%29%2B1+=+0
%28sqrt%282%29%2Acos%28x%29-1%29%5E2+=+0
sqrt%282%29%2Acos%28x%29-1+=+0
sqrt%282%29%2Acos%28x%29+=+1
cos%28x%29+=+1%2Fsqrt%282%29

x = 45 degrees or 315 degrees, plus or minus any multiple of 360 degrees.