As shown in the figure, AB is the diameter of circle O, C and D are two points on circle O. Connect AC, BC, CD, and OD respectively. If angle DOB = 140.0, then angle ACD = ()
Choices:
A:20°
B:30°
C:40°
D:.70°A70°
Please directly answer the question and provide the correct option letter, e.g., A, B, C, D.
Question: As shown in the figure, AB is the diameter of circle O, C and D are two points on circle O. Connect AC, BC, CD, and OD respectively. If angle DOB = 140.0, then angle ACD = ()
Choices:
A:20°
B:30°
C:40°
D:.70°A70°
Please first conduct reasoning, and then answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
Question: As shown in the figure, AB is the diameter of circle O, C and D are two points on circle O. Connect AC, BC, CD, and OD respectively. If angle DOB = 140.0, then angle ACD = ()
Choices:
A:20°
B:30°
C:40°
D:.70°A70°