Đáp án:

\(\begin{cases} \vec{n}_D = (1, 1, 1) \\ \vec{n}_Q = (1, -1, 1) \end{cases} \implies \vec{n}_R = [\vec{n}_D, \vec{n}_Q] = (2, 0, -2).\)

pt mp(R):  \(2x - 2z + D = 0\)

\(d(O, mp(R)) = 2 \implies \frac{|D|}{\sqrt{2}} = 2 \implies D = \pm 2\sqrt{2}.\)

Vậy:  mp(R): \( \Big[ \begin{aligned} mp(R): 2x - 2z + 2\sqrt{2} = 0 \\ mp(R): 2x - 2z - 2\sqrt{2} = 0\end{aligned}.\)