I seem to be missing something obvious here:
In the figure above, segments AD and AC divide angle EAB into three nonoverlapping angles that are equal in measure. Are AE and AB equal in length?
(1) AD = AC
(2) AC = CB
(1) since <EAD, <DAC, and <CAB are equivalent having sides AD = AC will have
to make AE = AB so SUFFICIENT
(2) if sides AC = AB, although <EAD, <DAC, and <CAB are equivalent side AE can continue to extend longer than AC or AB. There is no information here that states segment ADCB forms a linear line so it is INSUFFICIENT
is the answer