$\displaystyle T=\mathbb R^2 \: A=\mathbb Q^+ \times \mathbb R^+$

$\displaystyle \overline{A}=?$ /closure of A/

$\displaystyle Int A=?$

In $\displaystyle (A, \tau_A)$ is $\displaystyle A$ open? $\displaystyle (A, \tau_A)$ /topological space/

Thank you in advance!