Homework Help: Proving a given vector equation

1. The problem statement, all variables and given/known data
Prove ||u+v||^2 + ||u-v||^2=2||u||^2+2||v||^2

2. Relevant equations
* This is the part I can't figure out*

3. The attempt at a solution
anybody got an idea where I can start? I can't seem to remember the property I can use to simplify ||u+v||^2

P.S sorry for the vague title, i really didn't know what to put in there.

 

Yes! sorry I should have italized them , copy pasted it, Ill edit it right now

 

Hmmmm, Not too sure what I can say, but geometrically they are two sides of a parallelogram, and u+v / u-v is the line across it

 

Ahhh I see so I do u+v dot u+v ? then just distribute and use the idea that u dot u = ||u||?

 

nope lead me in the right direction. Thank you so much!