I need help on this question, I know the answer (or, at least I think I know it), but I can't think of the rest.

Bobby claims that only upright squares can have rational numbers for side lengths. Is he correct? Explain.

I got yes, he is correct, but I can't hink of an explanation besides common sense! Help, please?

2 answers

What is an upright square?
On a grid, an upright square is a square that is well, upright, on one of its sides, with the sides going along the grid points.