Mathematics and geometry in senior two, I can only prove that CD = DF and EF = CE. How can I prove their equivalence?
Very simple, the bisector of straight triangle ACD and ADF, AD angle, angle CDA= is called ADF, CH, DF is perpendicular to AB, angle BCH= angle BDF, angle CDE+ angle CED= 180, angle BDF+ angle DEF+ angle CED= 180, so angle CDE= angle CED.