The main problem I don't understand is that ad is not the middle line, and I can't get a picture. What picture is required to be drawn on the title? In the process of solving problem (2), have you found the method of "knowing the middle line on one side and the other side of the triangle, finding the length range of the third side"? If so, please solve the following problem: in △ ABC, AC = 5, middle line ad = 7, draw a picture and determine the length range of AB side

The main problem I don't understand is that ad is not the middle line, and I can't get a picture. What picture is required to be drawn on the title? In the process of solving problem (2), have you found the method of "knowing the middle line on one side and the other side of the triangle, finding the length range of the third side"? If so, please solve the following problem: in △ ABC, AC = 5, middle line ad = 7, draw a picture and determine the length range of AB side

I don't see the content of question (2). As far as the problem is concerned, I review "the sum of the two sides of a triangle is greater than the third side, and the difference between the two sides is less than the third side" and "the nature of the middle line"