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Homework Help: Similar triangles. How does 4/6 turn into 2h/3 ?

  1. Nov 5, 2012 #1
    1. The problem statement, all variables and given/known data

    r/h = 4/6

    This turns into: r = 2h/3

    How, can someone please refresh me? I am doing a related rates problem, and I for this! :(


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Nov 5, 2012 #2

    dextercioby

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    Isn't 4/6 = 2/3 ? (Everything is written in basis 10).
     
  4. Nov 5, 2012 #3

    Mark44

    Staff: Mentor

    r/h = 4/6 = 2/3

    Now multiply both sides of this equation by h.
     
  5. Nov 5, 2012 #4
    4/6 * x = 2x/3x ?

    Why is just 2x/3 ?
     
  6. Nov 5, 2012 #5

    dextercioby

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    The multiplication affects only the numerator. Think about it as (6/4)x5 = (6:4)x 5 = 6:4x5 = 6x5:4 = 30:4 = 7.5
     
    Last edited: Nov 5, 2012
  7. Nov 5, 2012 #6

    HallsofIvy

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    If you are doing things involving "related rates" and Calculus, I think we have right to assume that you can do arithmetic! 4/6= (2*2)/(2*3)= 2/3!!!
     
  8. Nov 5, 2012 #7

    Mark44

    Staff: Mentor

    And if this assumption by us is incorrect, then you are going to have a very difficult time in calculus.
     
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