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Maximum range problem, please help!

  1. Feb 28, 2012 #1
    Hey guys,

    I was hoping somebody might help me; I'm really confused. I obtained the formula for distance, which is this:


    And the derivative for distance, which is this:

    derivative of d with respect to alpha=0=(2[v_0]^2)/(gcos^2(beta))*(-sin(alpha)sin(alpha-beta)+cos(alpha)cos(alpha-beta))*cos(2alpha-beta)

    I was trying to see what alpha would be for maximum range, but I have no idea where the very end term on the right comes from: cos(2alpha-beta). Could somebody please me? Thank you.

  2. jcsd
  3. Feb 28, 2012 #2


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    Homework Helper

    Hey David! :smile:
    No, that *cos(2α-β) at the end must be a misprint for =cos(2α-β) …

    cos(A+B) = cosAcosB - sinAsinB :wink:
  4. Feb 28, 2012 #3
    Thank you very much Tiny-Tim! That was exactly what I needed! :D
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