Liuzhou 20 12 penultimate problem circle in the middle school entrance examination of mathematics. The following questions are attached.
Connect ODJIAO with AC at G, with OD=OB, ∠ODB=∠OBD=∠ABD, ODB, O as the midpoint, OG = AB/2 = 3bc/ 10, DG = OD-OG = BC/5, AE.