Vector Equation Proof: Finding the Magnitude of a Vector Sum

[Baumer8993]

Homework Statement

Prove llu+vll² + llu-vll² =2llull² + 2llvll²

Homework Equations

I am thinking I need to use some dot, or cross products.

The Attempt at a Solution

I just do not know where to start.

 

[CAF123]

Use what you know for finding the length of a vector (in terms of a dot product)and the associativity of the dot product.

 

[Baumer8993]

What do you mean by that?

 

[Dick]

What do you mean by that?

||a||^2=a.a, use that.

 

[Baumer8993]

Ohhh thanks! Now I get it.