∠ABC=∠ACB=∠D because AB=AC.

In △ Abe and △ Abd; ∠ABC=∠D，∠BAC=∠BAC

So, △ABE∽△ABD

So AB/AD=AE/AB

Because ad = 6 and AE = 2.

So AB=2 times the root number 3.

Absolutely original, I did this problem the day before yesterday! !