Question

The circle shown below has AB and BC as its tangents. If the measure of arc AC is 160°, what is the measure of angle ABC?

80°

40°

60°

20°

Answer 1

i will fan and medal

Answer 2

There a (at least) 2 ways to get the answer:
1) remember the "rule" the exterior angle ABC = ½ (difference between intercepted arcs)
2) draw some radiuses (radii if you are Latin) like this