∠DOF=90°
∠BOD=∠AOC
由∠EOD=∠BOD,则∠AOC=∠EOD
又OF平分∠AOE,则∠EOF=∠AOF
则有2（∠DOE+∠EOF）=180°
则∠DOF=90°
若∠AOC=28°,则∠EOF=90°-∠AOC=62°