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September 20, 2014

September 20, 2014

Posted by **Kate** on Saturday, July 23, 2011 at 12:19pm.

2cos2 x - 5cos x + 2 = 0?

A) 240 degrees

B) 135 degrees

C) 270 degrees

D) 90 degrees

- Math -
**Reiny**, Saturday, July 23, 2011 at 12:42pmI will read that as

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.

Check your typing

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