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Homework Help: Equations of Lines and Vectors

  1. May 4, 2010 #1
    1. The problem statement, all variables and given/known data

    Find the coordinates of three points on each of the following lines.
    a. (x+2)/3=(y-1)/2=(z+5)/(-3)
    x = -1 + 5t

    b.y = 7 + t
    z = 3 - 2t



    2. Relevant equations

    (x+2)/3=(y-1)/2=(z+5)/(-3)
    x = -1 + 5t

    y = 7 + t
    z = 3 - 2t


    3. The attempt at a solution

    I'm guessing that they mean the (x,y,z) coordinates by saying "Find the three coordinates." I attempted a), and found the three coordinates to be (-3.5,0,-3.5), but am unsure if this is correct. I also am lost on how to attempt the second one, b).

    any help is appreciated!
     
  2. jcsd
  3. May 4, 2010 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi spoc21! :smile:
    No, I think they mean find any three points on the line.

    For the second one, just use any three values of t. :wink:
     
  4. May 4, 2010 #3
    Thanks tiny-tim,

    so basically, I will need to find three points for each line (therefore use three different values for t) so that I get:

    [x1, y1, z1]

    [x2, y2, z2]

    [x3, y3, z3]

    Thanks again!
     
  5. May 4, 2010 #4

    Mark44

    Staff: Mentor

    No, you should get specific points - with numbers, not variables.
     
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