Answer:
100 degrees
Step-by-step explanation:
Remember: an angle subtended by the circumference is always 1/2 the angle subtended by the center. (unless the angle subtended by the circumference is inside the angle subtended by the center).
In other words, C could be anywhere except between B and A, and angle ADB will be twice as large as angle ACB.
Therefore, angle ACB = 50*2=100 degrees
