Câu fifteen. ?? dài trung tuy?n mc ?ng v?i c?nh c c?a DABC b?ng bi?u th?c nào sau ?âyT?t C?Tin H?c L?p 6Tin H?c L?p 7Tin H?c L?p 8Tin H?c L?p 9Tin H?c L?p 10Tin H?c L?p 11Tin H?c L?p twelveT?t C?Th? D?c L?p 10Th? D?c L?p eleventh? D?c L?p 12Th? D?c L?p sixth? D?c L?p seventh? D?c L?p 8Th? D?c L?p 9H? tr?i nghi?m, h??ng nghi?p three SGK Ho?t ??n