For the isosceles trapezoid ABCD, ad is parallel to BC, ad = 2cm, BC = 8cm, e is the midpoint of the lumbar CD, be divides the trapezoid into two parts, the perimeter difference is 3cm, and calculates the length of ab I only have the second grade of junior high school, and I am learning the median line of triangle and trapezoid. I hope you can help me solve the problem according to the direction of this theorem

For the isosceles trapezoid ABCD, ad is parallel to BC, ad = 2cm, BC = 8cm, e is the midpoint of the lumbar CD, be divides the trapezoid into two parts, the perimeter difference is 3cm, and calculates the length of ab I only have the second grade of junior high school, and I am learning the median line of triangle and trapezoid. I hope you can help me solve the problem according to the direction of this theorem

Let AB = X
(1) If the perimeter of a quadrilateral is shorter than that of a triangle, then
X+2+BE+DE+3=8+BE+CE
Because de = CE
X+2+3=8
X=3
Because 3 + 2 + 3 = 8, these four sides cannot form a trapezoid
(2) If the quadrilateral is longer than the circumference of the triangle, then
X+2+BE+DE=8+BE+CE+3
X=11-2=9
AB=9