# Math

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Which of the following is a solution to the trigonometric equation
2cos2 x - 5cos x + 2 = 0?

A) 240 degrees
B) 135 degrees
C) 270 degrees
D) 90 degrees

• Math -

2cos^2 x - 5cos x + 2 = 0
(2cosx - 1)(cosx - 2) = 0
cosx = 1/2 or cosx = 2, the last part of course is not possible

so cosx = 1/2
x = 60° or 300°

So none of your choices work.
Both of my answers work in the original equation.

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