Answer:
The sum of the interior angles of any polygon is (n-2)*180° (n being the number of sides) so for a triangle the sum of the interior angles is 180°. The sum of the interior and exterior angles is also 180°. To work out which sets are possible you subtract each number from 180° and then add all three answers together. If you get 180° then that set of numbers is possible. Using this method, you will find that the following sets can be the measures of the exterior angles of a triangle:
Explanation:
120°, 110°, 130°
120°, 120°, 120°