Let ∠ ADC = 2β
Ac and BD are perpendicular bisectors of each other ⇒⇒ (Given information)
∴ BD bisects the angle ADC
∴ ∠ADE = 0.5 ∠ADC = β
And in ΔADE:
∵∠DEA = 90° ⇒⇒⇒ from the given information
∴∠DAE = 90° - β
And AC bisects ∠DAB ⇒⇒⇒ from the given information
∴∠EAB = ∠DAE = 90° - β
