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: Is this any kind of proof?

  1. Mar 22, 2010 #1
    http://img405.imageshack.us/img405/8026/prover.jpg [Broken]

    I would say it's pretty weak, how could I improve upon it?

    It's supposed to be the triangle inequality.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Mar 22, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    I don't mean to be rude, but frankly: it's not a proof at all. It's just two columns with a list of things that seem to be unrelated, and something that looks like what you wanted to prove at the bottom.

    How about you use the definition of norm, as
    [tex]|\vec{v}|^2 = \vec v \cdot \vec v[/tex]
    and work out
    [tex]|\vec{u} + \vec{v}|^2[/tex]
  4. Mar 22, 2010 #3
    I'm just going off of the material presented in the chapter of a calc/linear algebra book, it is the first chapter and hasn't touched on anything further.

    [tex] \overline{A} \overline{B} \ + \ \overline{B} \overline{C} \ = \ \overline{AC} [/tex]

    if I'm not mistaken, then I went to normalize the vectors but I think I got it wrong.

    I'll just keep reading...
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook