Ko kho' da^u, suy nghi chut la` ra tho^i
Goi y' de ban suy nghi trc' , neu chua la`m duoc thi` tui moi' giai
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De ba`i cho tro.ng ta^m G va` MN // AC
Hay loi dung tinh' chat Tam giac dong dan.g va` tinh chat trong ta^m
Ban hay ke BG, cat AC tai K, theo tinh chat duong trung tuyen thi` ta co' ti le^, BG/BK = 2/3
Nhu vay BM/AB cung bang 2/3. Nhu vay MN/AC cung bang 2/3, BN/BC cung bang 2/3
Nha'c lai. cho ban kien thu'c ve phan so^', neu nhu*:
A/B = C/D ===> A/B = C/D = (A+C) /(B+D)
Vi' du : 1/2 = 3/6 = (1+3)/(2+6) = 4/8 = (3+4)/6+8) =.....
Nhac them cho ve^` ta'ch doan, AB = MB + AM, BC = BN + NC