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Math Help - need help

  1. #1
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    need help

    1)in a triangle, if A=2B prove that a^2=b^2 + bc
    2)in a triangle, if a+c=2b prove that cot(C/2) = 3 tan(A/2)
    PS please dont use calculus to solve!
    Last edited by calculus_jy; June 19th 2007 at 01:58 AM. Reason: sorry big typo
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by calculus_jy View Post
    1)in a triangle, if A=2B prove that a^2=B^2 + bc
    In general there is a difference between the variables "b" and "B." When referring to triangles B tends to represent the angle across from the side of length b. The first question, with a^2 = B^2 + bc then, makes no sense. Even if you meant b = B, there are a variety of triangles with the property A = 2B with different values of c so the proposed equality need not be true.

    -Dan
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  3. #3
    Math Engineering Student
    Krizalid's Avatar
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    Quote Originally Posted by calculus_jy View Post
    1)in a triangle, if A=2B prove that a^2=B^2 + bc
    Mmmm

    Given \triangle{ABC} where \measuredangle~A=2\cdot\measuredangle~B then a^2=b(b+c)

    It's a well known property.
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  4. #4
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    sorry for wasting ur time,
    i made a mistake in typeing B when i meant b and i already know that in a triangle AB=c AC=b and BC= a,

    when i posted it, i actually want to c the prove, however, i hav already proven it, so dont worry about it
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