BBACC dbdbdbdbc 1 1。 -2 or1/312.613.4/514.cm =1/4e65438+. CN = 1/2e 1+ 1/2e 2； CP = 3/4e 1+ 1/4e 2. 15。 GF = CF-CG =-1/2b+1/2a, so GK =1/2 (GD+GF) =1/2 (-1/2a-) DF = cf-。 There are three * * * lines of D, H and F, so there is a real number n, which makes DH = NDF = N (A- 1/2b). Because AD+DH = Ah, (1-n/2) B+Na = MB+m=4/5 2a. That is ah = 4/5 (b+1/2a) = 2/5 (a+2b).16. Because a is the midpoint of BC, OA = 1/2 (ob+oc), that is, oc = 20a-ob = 2a-b.