6:05 AM
.
I was thinking about the set $\{(x,y)| x^2+y^2 = \frac{1}{n^2}, n \in \Bbb{N}, x\in \Bbb{Q}$ or $y \in \Bbb{Q}\}$ Certainly, this set is non-empty as I can find a pair $(\frac{1}{n^2},0)$ or like $(\frac{1}{2n^2},\frac{1}{2n^2})$ or in a more genral sense the points of the form \$(\frac{a}{n^2},\...