Answer:
a) m arc AD = 145
b) D = 10
Step-by-step explanation:
a) mAD can be found because triangle OCM can be shown to be congruent to triangle ODM.
The angle AOD is supplementary to DOB which we just showed to be congruent to the known 35° angle COB. Therefore AOD = 180 - 35 = 145°
The arc length is identical to the arc angle when measured between radii.
b) The radius OC = √(OM² + (CD/2)² = √(3² + 4²) = 5.
Diameter is twice radius = 10