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Math Help - x = tanx

  1. #1
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    x = tanx

    Can someone explain to me why xcosx - sinx = 0 when x = tanx?

    Thanks.
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  2. #2
    MHF Contributor ebaines's Avatar
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    Re: x = tanx

    Replace tanx with sinx/cosx and it comes right out.
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  3. #3
    Forum Admin topsquark's Avatar
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    Re: x = tanx

    Asked and answered in the other thread.

    Please do not double post.

    -Dan
    Last edited by topsquark; November 6th 2012 at 05:30 PM.
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  4. #4
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    Re: x = tanx

    Let x = tan x. Then

    x cos x - sin x
    = tan x * cos x - sin x
    = (sin x / cos x) * cos x - sin x
    = sin x - sin x
    = 0
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