If AB = 4, AC = 6, then the value range of ad is___ .

If AB = 4, AC = 6, then the value range of ad is___ .


As shown in the figure, extend ad to e, so that de = ad, ∵ ad is the middle line on the edge of BC, ∵ BD = CD, in △ abd and △ ECD, ∵ BD = CD ∠ ADB = ≌ edcde = ad, ≌ abd ≌ ECD (SAS),