Question

BD is a diameter of circle O. If mABC=30, what is the mDBA

Answer 1

Question:

DB is a diameter of circle O. If mACB = 30°, what is the mDBA?

(a) 30° (b) 50° (c) 60° (d) 70° (e)90º

Solution:

(Angle subtended by the diameter is 90º)

∠DAB = 90º

(angles in a circle formed by the same arc are equal)

∠ ADB = ∠ACB

∠ ADB  = 30º

(Sum of angles in a triangle is 180º)

∠DBA = 180 - 90 - 30

∠DBA = 60º

Answer: (c) ∠DBA = 60º

Answer 2

Answer: it's just 60 believe me

Step-by-step explanation: