Lets O is the center of the circle and Lets A is a point cut on CD from O
mCD = m<COD
OA is perpendicular bisector of CD so OA = 1/2 CD = 1/2(12.7) = 6.35
Sin (DOA) = AD/OD = 6.35 / 9.06
Sin DOA = 0.7009
<DOA = 44.5°
<COD = 2 x 44.5°
<COD = 89°
mCD = <COD = 89°
Answer: 89°
