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对于一些非圆的平面几何问题,在适当的条件下,通过构造圆,会得到简捷的解决。例1如图(1),在△ABC和△DEF中,已知∠A=∠D=70°,∠B=50°,∠E=30°,画直线m、n,使直线m将△ABC分成两个小三角形与直线n将△DEF分成两个小三角形相似.并标出每个小三解形各个内角的度数.不要求写出画法,只要画出一种分法)
For some non-circular plane geometry problems, a simple solution can be obtained by constructing a circle under proper conditions. Example 1 As shown in (1), in △ABC and △DEF, it is known that ∠A=∠D=70°, ∠B=50°, ∠E=30°, and draw straight lines m and n so that the straight line m will be △ ABC is divided into two small triangles and a straight line n, which is similar to dividing △DEF into two small triangles. The number of degrees of the internal angles of each small three demangle is marked. There is no need to write the painting method, just draw a division method.)