The last question of Nanjing senior high school entrance examination in senior high school mathematics 20 14
You can draw a picture and analyze it. Regardless of Jing You's answer. Otherwise your answer is wrong!
According to the research of (1) (2) (3), it is necessary to add the condition that triangle ABC and triangle DEF are the same type of triangles (that is, they are all obtuse triangles, right triangles or acute triangles).