# Homework Help: Vectors question help

1. Mar 6, 2014

### noahsdev

1. The problem statement, all variables and given/known data
If two linearly independent vectors are of equal magnitude, prove that their sum is perpendicular to their difference.

2. Relevant equations
v1.v2 = 0

3. The attempt at a solution
This question doesn't seem that hard but it's really confused me.
Help is appreciated, thanks.

2. Mar 6, 2014

### vanhees71

Just write down the scalar product!

3. Mar 6, 2014

### HallsofIvy

This is a "relevant equation" only if you say what v1 and v2 are! In particular are you clear that v1 and v2 are NOT the "two linearly independent vectors" of the question? Call the two vectors u and v. Their sum is u+ v and their difference is u- v. So "their sum is perpendicular to their difference" means (u+ v).(u- v)= 0. What does the fact that they are linearly independent tell you?

4. Mar 6, 2014

### Staff: Mentor

noahsdev, per Physics Forums rules, you must show what you have tried when you post a question.