1. This question mainly examines the practice of auxiliary lines when the midpoint, vertical line and angular bisector appear. By observing the figure, we can construct an isosceles triangle, and put the known conditions together, so that we can make auxiliary lines: extend BE to G, make EG=BE, connect CG and GD, and extend AF to GC to H. Using these new conditions, we can find the equivalent relationship between line segments.
2. For auxiliary lines with midpoints, vertical lines and angular bisectors, there are generally: ① construction midline; ② Construct symmetrical figures. As for which method to choose, it is necessary to combine the problem map with the known conditions. In this topic, we extend BE to G, make EG=BE, connect CG and GD, and extend AF to GC in H. Combining with the known conditions, we can conclude that △BDG is an isosceles triangle. Please think about which method to use.
3. In the problem of midpoint, vertical line and angular bisector, the knowledge of midline and similar shape is often the key to solving the problem, and it is also the content we must master. ?
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