SOLUTION: Please help me...Find to the nearest degree, all values of x in the interval 0<x<180 that satisfy the equation 8co

Algebra ->  Expressions-with-variables -> SOLUTION: Please help me...Find to the nearest degree, all values of x in the interval 0<x<180 that satisfy the equation 8co      Log On


   



Question 197737: Please help me...Find to the nearest degree, all values of x in the interval 0
the equation 8cos^2x-2cosx - 1= 0. Thanks so much!

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Find to the nearest degree, all values of x in the interval 0
the equation 8cos^2x-2cosx - 1= 0
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Factor:
(4cos(x)+1)(2cos(x)-1) = 0
cos(x) = -1/4 or cos(x) = 1/2
x = 104.48 degrees or x = -104.48 degrees
or
x = 60 degrees or x = -60 degrees
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Cheers,
Stan H.