📢 QuizNe.vn will officially cease operations on 27/08/2026. Thank you for being with us.
- $ \\\frac{{2\\\sqrt 3 {a^2}}}{9}.$
- $ \\\sqrt 3 {a^2}.$
- $ \\\frac{{2\\\sqrt 3 {a^2}}}{3}.$
- $ 2\\\sqrt 3 {a^2}.$