Bai 20: Tu dien ABCD co A (1, 2, -1), B(0, 1, 3), C(2, 0, 4), D ( - l , 2, 0). Tim M e (ABC) de |MO - MDl Ion nhat
Bai 21: Lap phuong trinh mat phang qua M (2, 5, 4) va cat
cac tia Ox, Oy,
Oz tai A, B, C ma the tich hinh chop O.ABC be nhat. HD: diing phuong trinh doan chan va bat da[r]