Pythagoras

So we all know that to find the length of a hypotenuse you use the formula A squared + B squared = C squared.  What happens, however, if A and B = 1 ?  Did Pythagoras note this problem?  Is 2 the only number with an infinite decimal for a square root?  How do you find the length of the hypotenuse in this situation?  

That's not more specifically, that's more in general.