We can't see the whole question. :/
You only need one if you follow a pattern of
top left dot
top middle dot
middle middle dot
middle left dot
bottom left dot
bottom middle dot
bottom right dot
middle right dot
top right dot
The diameters intersect at the center of the circle
m<BKD = 100
<AKC is vertical to <BKD, so m<AKC = 100
An arc has the same measure as its central angle,
so m(arc)AC = 100
