Do EM⊥AN in M, GH⊥AN in H, MN in EG in O.

AB = AE，

∠ class +∠ ABN = 90, ∠ EAM+∠ class = 90, then ∠ABN=∠EAM.

∠ANB=∠AME=90

∴△ABN≌△AEM(AAS)

∴AN=EM,S△ABN=S△AEM

Similarly: △ ACN △ AGH (AAS)

Then S△ACN=S△AGH, GH=AN.

∴GH=EM

∠∠MOE =∠HOG，∠EMH=∠GHO=90，GH=EM

∴△EMO≌△GHO(AAS)

∴S△EMO=S△GHO

∫S△ABC = S△ABN+S△ACN

=S△AEM+S△AGH

S△AEG = S△AEO+S△ before

=S△AEM-S△EMO+S△AGH+S△GHO

=S△AEM+S△AGH

∴S△ABC=S△AEG