Answer:
The correct answer is:
1. Because of collinearity and supplementarity-
2. They remain along the same line.
3. The sum of them is 180 degrees.
4. Supplementarity.
5. The sum of the internal angles of a triangle is 180ª
6. Supplementarity and external angle theorem sum up the same.
7. Nothing.
Explanation:
1. The reason why the exterior angle of 3 is 4, its because the last one is supplementary and collinear to the other.
2. Angle 3 and 4, form a collinear pair since they remain along the same line.
3. Angle 3 is supplementary to 4 because the sum of them is 180 degrees.
4. The sum of the angles are 3 and 4 is 180 because they are supplementary.
5. The sum of the angles mentioned is: 180 because of internal angle theorem.
6. It's like that because supplementarity and external angle theorem sum up the same. i.e, angle 1 + angle 2 + angle 3 = angle 3 + angle 4 =180
7. Nothing.