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Math Help - finding and angle x in radians?

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    finding and angle x in radians?

    Find an angle x in radians such that 8pi<x<9pi and cosx=1/2

    What is this question asking for? I came up with pi/3, but I don't think that's in between 8 and 9 pi. Can anyone explain? Thanks
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    Quote Originally Posted by captaintoast87 View Post
    Find an angle x in radians such that 8pi<x<9pi and cosx=1/2

    What is this question asking for? I came up with pi/3, but I don't think that's in between 8 and 9 pi. Can anyone explain? Thanks
    Remember that \cos{x} is periodic with a a period of 2\pi which means you get your original answer of \frac{\pi}{3} and add 4 lots of 2\pi (this is 4 periods) to give you an answer of 8\pi + \frac{\pi}{3} = \frac{25\pi}{3}
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