Use the Triangle angle sum theorem to the measure of the angle on point C
The Triangle angle sum theorem states that the sum of the interior angles of a triangle is always 180 degrees.
In triangle ABC, we know that angle A measures 60 degrees and angle B measures 40 degrees.
So, the measure of angle C can be found by subtracting the sum of angles A and B from 180 degrees:
Angle C = 180 degrees - (60 degrees + 40 degrees)
Angle C = 180 degrees - 100 degrees
Angle C = 80 degrees
Therefore, the measure of angle C is 80 degrees.