In the diagram below, DC, AC, DOB, CB, and AB are chords of circle O, FDD is
tangent at point D, and radius AO is drawn. Sam decides to apply this theorem to the diagram: "An angle inscribed in a semi-circle is a right angle."
E
3.
F,
Which angle is Sam referring to?
(1) LAOB
(2) LBAC
(4) LFDB
(3) LDCB