###### Asked in Math and ArithmeticTrigonometry

Math and Arithmetic

Trigonometry

# What are the solutions of 2 cos squared x minus cos x equals 1?

## Answer

###### Wiki User

###### November 12, 2010 5:42AM

2cos2x - cosx -1 = 0

Factor:

(2cosx + 1)(cosx - 1) = 0

cosx = {-.5, 1}

x = {...0, 120, 240, 360,...} degrees

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