Answer:
I think it's A AND C. The diameter is just the radius multiplied by 2 at the end of the day.B is just wrong.
Answer:
7/6
Step-by-step explanation:

Answer:
BCD = 60
ABD - 90
Step-by-step explanation:
BCD)
BC and CD are the same length on in the circle, they are the radius. Therefor, all angles will be the same at 60
ABD)
All angles together are 180
You know 2 Angles, A at 30 and D at 60
180 - 30 - 60 = Angle B
90 = Angle B