A ) ∠ BDA = 60°
∠DBA = 30°
B ) sin (∠DBA ) = sin 30° = 1/2
C ) arc AB = 1/3 · 2 r π = 1/3 · 18 π = 6 π = 6 · 3.14 = 18.84 cm
D ) arc AD : arc AB = 1 : 2
E ) Degree measure of an arc is equal to the measure of the central angle that intercepts the arc. The degree measure is 60° ( F E = 9 cm, r = 9 cm ).