SOLUTION: Solve the equation for the interval [0,2π) cosē(x)+2cos(x)+1 = 0 The answer I know that is: π , but how to you do it?

Algebra ->  Trigonometry-basics -> SOLUTION: Solve the equation for the interval [0,2π) cosē(x)+2cos(x)+1 = 0 The answer I know that is: π , but how to you do it?       Log On


   

Question 978446: Solve the equation for the interval [0,2π)
cosē(x)+2cos(x)+1 = 0
The answer I know that is: π , but how to you do it?
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!

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Use u-substitution:

Let u = cos(x)

u%5E2%2B2u%2B1%22%22=%22%22%220%22

%28u%2B1%29%28u%2B1%29%22%22=%22%22%220%22

%28u%2B1%29%5E2%22%22=%22%22%220%22

u+1 = 0
  u = -1

Substitute cos(x) for u

cos(x) = -1

     x = p

Edwin