Homework Help: Is this any kind of proof?

1. Mar 22, 2010

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. Mar 22, 2010

CompuChip

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
$$|\vec{v}|^2 = \vec v \cdot \vec v$$
and work out
$$|\vec{u} + \vec{v}|^2$$

3. Mar 22, 2010

$$\overline{A} \overline{B} \ + \ \overline{B} \overline{C} \ = \ \overline{AC}$$