http://diendantoanhoc.net/topic/151173-h%E1%BB%8Fi-th%C3%A1p-tam-gi%C3%A1c-v%E1%BB%9Bi-%C4%91%E1%BB%99-cao-l%C3%A0-244-c%C3%B3-bao-nhi%C3%AAu-h%C3%ACnh-tam-gi%C3%A1c/
http://diendantoanhoc.net/topic/151173-h%E1%BB%8Fi-th%C3%A1p-tam-gi%C3%A1c-v%E1%BB%9Bi-%C4%91%E1%BB%99-cao-l%C3%A0-244-c%C3%B3-bao-nhi%C3%AAu-h%C3%ACnh-tam-gi%C3%A1c/
khong biet co ban nao biet cho mk biat voi cam on
Trời đất công thức - kq ( Thật ra cháu cx chẳng biết j ) T_T