38 30 6 2014 DtHfyalj^ Khai thac sau hinh hpc khong gian bing tirofng tir hoa bai toan phang H O A N G V A N B A U X udt phat tir bai t o ^ hinh hpc ph&ig co ban Cho khoi chop S ABC tren c ^ canh SA,[.]
38 30 6-2014 DtHfyalj^ Khai thac sau hinh hpc khong gian bing tirofng tir hoa bai toan phang H O A N G VAN BAU udt phat tir bai t o ^ hinh hpc ph&ig co ban Cho khoi chop S.ABC tren c ^ canh SA, SB, SC Isui ^sau va xem no nhu la bai toan goc va luot lay cac di6m A', B', C khac A Chihig mlnh SA' S B ' S C tuong tu hoa bai toan sang khong gian va rang: V , A , Trong d