$$\overline{Q}=\overline{m}-2\overline{n}; \overline{6}=2\overline{m}+2\overline{n}; |\overline{m}|=1; \varphi=\frac{\pi}{4}$$
$a=m-2\pi b$
$m\in \mathrm{R}$
$b\in \mathrm{R}$
