Answer:
m∠ABC = 40°
Explanation:
Line BC divides the circle into two parts, so the measure of Arc BC is 180°. Then, the measure of arc AC is equal to:
Arc AC = Arc BC - Arc AB
Arc AC = 180° - 100°
Arc AC = 80°
Then, the measure of arc AC and the m∠ABC are related as:
m∠ABC = 1/2(Arc AC)
So, m∠ABC is equal to:
m∠ABC = 1/2(80)
m∠ABC = 40°
Therefore, the answer is 40°
