1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Line Segment

  1. Feb 23, 2009 #1
    1. The problem statement, all variables and given/known data

    Find the directed line segment joining (1,1,1) to (1,3,1)

    2. Relevant equations

    3. The attempt at a solution

    (1,1,1) + (0,2,0)t is that correct?
  2. jcsd
  3. Feb 23, 2009 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Is it a directed line segment?
    Does it start at (1,1,1)?
    Does it end at (1,3,1)?

    If so, then it's correct.
  4. Feb 23, 2009 #3


    User Avatar
    Science Advisor

    Notice the "start and stop". You will need conditions on t as well as, for the "directed" part, something like "as t goes from ___ to ___".
  5. Feb 23, 2009 #4
    you mean like this:

    for all t [tex]\rightarrow \Re[/tex]

    or what im trying to say is that for all t that are real numbers (couldn't find the symbol for it; looks like a small 'e')
  6. Feb 23, 2009 #5


    User Avatar
    Science Advisor

    No, the whole point is that t cannot be "all real numbers". That could give the entire line, not the line segment. And you still haven't dealt with the "directed" part. Do you understand the difference between a line segment and a line? Do you understand what a directed line or directed line segment is?
    Last edited by a moderator: Feb 24, 2009
  7. Feb 23, 2009 #6
    [tex]0 \leq t \leq 1[/tex]
  8. Feb 24, 2009 #7


    User Avatar
    Science Advisor

    Okay, that gives the "segment". Now what about the "directed" part? Unfortunately, your original statement of the problem doesn't give a direction. You just said "the directed line segment joining (1,1,1) to (1,3,1)" which does not state a direction. Is the direction from (1, 1, 1) to (1, 2, 1) or from (1, 2, 1) to (1, 1, 1)?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook