∠EAB+∠BAC+∠ABF+∠ABC=2*180
(∠EAB+∠ABF)+(∠BAC+∠ABC)=360
(2∠DAB+2∠DBA)+90=360
2(∠DAB+∠DBA)=270
2(180-∠D)=270
2∠D=90
∠D=45