3.
如左图所示,在\(\Delta ABC\)中,点\(O\)是\(AC\)上一点,过点\(O\)的直线与\(AB,BC\)的延长线分别相交于点\(M,N\).
【问题引入】\((1)\)若点\(O\)是\(AC\)的中点,\(AM\):\(BM=2:5\),求\(\dfrac{CN}{BN}\)的值;
温馨提示:过点\(A\)作\(MN\)的平行线交\(BN\)的延长线于点\(G\).
【探索研究】\((2)\)若点\(O\)是\(AC\)上任意一点\((\)不与\(A\),\(C\)重合\().\)求证:\( \dfrac{AM}{MB}· \dfrac{BN}{NC}· \dfrac{CO}{OA}=1 \);
【拓展应用】\((3)\)如右图所示,点\(P\)是\(∆ABC \)内任意一点,射线\(AP,BP,CP\)分别交\(BC,AC,AB\)于点\(D,E,F.\)若\(AF:BF=2:5\),\(BD:CD=2:3\),求\(\dfrac{AE}{CE}\)的值.