trong kgian toa do oxyz cho mat cau (S): (x-1)^2 +y^2 +(z-1)^2=4. va diem A(0;1;1) , B(-1;-2;-3) , C(1;0;-3). Tim diem D thuoc mat cau (S) sao cho the tich khoi tu djen ABCD lon nhat