# Proof question - Orthogonal Vectors

• Apr 5th 2011, 11:22 PM
Ife
Proof question - Orthogonal Vectors
I can never seem to prove these things. I have a practice question and I'm not sure how the layout should be.

Suppose a vector y is orthogonal to vectors u and v. Show that y is orthogonal to the vector u+v.

I know the basic rules for what makes vectors orthogonal but when I have to generalise that to show stuff like this i get totally lost. Any help please?
• Apr 6th 2011, 12:04 AM
FernandoRevilla
$=+=0+0=0$
• Apr 6th 2011, 12:06 AM
Ife
Ok, I am not sure i understand what you mean by <y,u>? is this the coordinate representation of a vector?
• Apr 6th 2011, 12:10 AM
FernandoRevilla
Quote:

Originally Posted by Ife
Ok, I am not sure i understand what you mean by <y,u>? is this the coordinate representation of a vector?

It is one of the notations for the inner product: $=y\cdot u=(y|u)$ etc.
• Apr 6th 2011, 12:10 AM
Deveno
you may know <y,u> as the "dot product".
• Apr 6th 2011, 12:12 AM
Ife
ohh. i haven't seen it like that as yet, i think.. thanks :)