What is the measure of DB if AF is 105o?

Question

What is the measure of  if  is 105^o?

75 degrees

65 degrees

60 degrees

55 degrees

None of these

Answer 1

measure of angle AEF = 1/2(arc AF + arc BD)

essentially AEF is the AVERAGE of the 2 arcs.

AEF = 90º

AF = 105º

90 = 1/2(105 + ?)

180 = 105 + ?

180 - 105 = ?

75 = ?

Answer 2

m AF = m AD

m DBF = 360° - m FAD

m DB = (1/2) m DBF