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Math Help - Roots of equation

  1. #1
    Member
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    Jerusalem - Israel
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    Roots of equation

    Hi, can anyone help me to prove this:

    If the roots of the equation

    x^3-Lx^2+mx+n=0

    are the cosine of the angles of a triangle

    show that: L^2=2m+2n+1
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  2. #2
    MHF Contributor
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    Re: Roots of equation

    Well, you have three angles. Use them and see what happens.

    \alpha, \beta, \pi - \alpha-\beta

    You have a Law of Cosines.

    Show us what you get.
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