Distance from curve to origin

[lockedup]

Homework Statement

Find the shortest distance from $$x^{2}-y^{2}=1$$ and the origin.

I was gone when my professor taught on this. I just want some hints to get started...

Homework Equations

The Attempt at a Solution

I graphed it and it's pretty easy to see that the answer is one. I just don't know how to prove it...

 

[ideasrule]

The square of distance is x^2+y^2, so you have to minimize that. Can you express x^2+y^2 in terms of only one variable?