I need to prove that ||u-v|| = 2^(1/2) if {u,v} is an orthonormal set in the vector space V.

Here is what I have so far, but do not know if I am even on the right page:

||u-v|| = <u-v, u-v>^(1/2), which is the definition of distance between vectors

But where do I go from here?

Thanks for any help.