Homework Help: Prove that this vector is equal to this?

1. Apr 27, 2010

Cuisine123

1. The problem statement, all variables and given/known data
Prove that |$$\vec{A}$$|2+|$$\vec{B}$$|2 equals to $$\frac{1}{2}$$(|$$\vec{A}$$+$$\vec {B}$$|2+|$$\vec{A}$$-$$\vec{B}$$|2)

2. Relevant equations
Perhaps the triangle inequality? I am not sure.

3. The attempt at a solution
I have no idea how to approach this question. Please help me with clear explanations. Thank you.

2. Apr 27, 2010

tiny-tim

Last edited by a moderator: Apr 25, 2017