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The reasoning of two math problems in the second day of junior high school!
2. Since DF is parallel to BE and DE is parallel to BF, the quadrilateral DEBF is a parallelogram, so BE=DF, so AE=CF, so all triangles ADE are equal to triangle CBF(SAS), so CF=AE.

3. It is proved that triangle ABE is equal to triangle CDF(SAS), so angle AEB= angle CFD and angle AEF= angle CFE, so AE is parallel to CF.