我们从1993年京、津、沪三市的中考试题中挑选了几道综合题,看看怎样应用恰当的方法,迅速地找到解题的思路. 例1 已知:如图1,△ABC是O的内接三角形,∠BAC的平分线交BC于F,交O于D.DE切O于D,交AC的延长线于E,连结BD,如果BD=3(2~(1/2)),DE+EC=6,AB:AC=3:2,求BF的长.(北京市) We selected several comprehensive questions from the middle school examination questions in the three cities of Beijing, Tianjin, and Shanghai in 1993 to see how to apply appropriate methods and quickly find a solution to the problem. Example 1 Known: As shown in Figure 1, △ABC is Inscribed triangles of O, ∠ BAC bisector intersects BC at F, intersect O at D.DE cut O at D, cross AC at E, connect BD, if BD=3(2~(1/2) ), DE+EC=6, AB:AC=3:2, find the length of BF. (Beijing)