Answer
Find out the measure, in degrees, of angle ABC .
To prove
The relationship between inscribed angles and their arcs
The measure of an inscribed angle is half the measure the intercepted arc.
The formula is
As given in the diagram
The measure of the intercepted arc A to B is 120°.
Put value in the formula
∠ABC = 60°
Therefore the measure of the ∠ABC is 60° .