E. F is two points on the edge BC of triangle ABC, and be = CF, connecting AE and AF. proof: ab + AC is greater than AE + AF

E. F is two points on the edge BC of triangle ABC, and be = CF, connecting AE and AF. proof: ab + AC is greater than AE + AF

Take the midpoint o of BC, connect and extend Ao to D, make od = OA, connect BD, ED, FD and CD, and then extend AE to intersect BD to g, then the quadrilateral abdc is a parallelogram
∴BD=AC,∴AB+AC=AB+BD.
∵OB=OC,BE=CF,∴OE=OF,
The quadrilateral AEDF is also a parallelogram
∴DE=AF,AE+AF=AE+DE.
In △ ABG, AB + BG > AG, that is ab + BG > AE + eg,
In △ DEG, eg + DG > De,
∴AB+BG+EG+DG
>AE+EG+DE,
∴AB+BD>AE+DE.
AB + AC > AE + AF