Answer:
m∠DBA = 60º
Step-by-step explanation:
Angle subtended by the diameter is 90º :
⇒ m∠DAB = 90º
Angles in a circle formed by the same arc are equal :
⇒ ∠ ADB = ∠ACB
⇒ m∠ ADB = 30º
Sum of angles in a triangle is 180º :
⇒ m∠DBA + m∠DAB + m∠BDA = 180º
⇒ m∠DBA = 180° - 90° - 30°
⇒ m∠DBA = 60°
