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How can I get the intersection of these lines

  1. May 8, 2012 #1
    1. The problem statement, all variables and given/known data
    Kindly view my 1st attachment. I need help to get the intersection of the highest line and the line extended by a slope from the horizontal line.


    2. Relevant equations
    y=mx+b
    y-y1=m(x-x1)


    3. The attempt at a solution
    Kindly view my 2nd attachment.
    By substitution, I always get the answer -1.87 which is obviously wrong. The answer should be lesser than -5.5.

    Thanks in advance.
     

    Attached Files:

  2. jcsd
  3. May 8, 2012 #2

    danago

    User Avatar
    Gold Member

    The first equation (y = x+105.5) is not quite correct. The gradient does have a magnitude of 1, however the line slopes downwards along the x-axis, therefore the gradient should be -1, not +1 as you have used. See if that fixes the problem.
     
  4. May 8, 2012 #3
    thanks, i'll work on it
     
    Last edited: May 8, 2012
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