Answer:
45°
Step-by-step explanation:
DF = EF
Angle F = 90°
Angle E = Angle F
Let Angle E and Angle F be x
x + x + 90° = 180° (Angle Sum Property)
2x + 90 = 180
2x = 180 - 90
2x = 90
x = 90/2
x = 45°
