In the image above, lines m and n are parallel, while t is the transversal line. The angles formed due to the intersection of parallel lines by the transversal line are listed from 1 to 8. The types of pairs of angles formed with equal measures are as explained below;

Alternate Interior angles; refer to two angles on the interior side of the parallel lines and on opposite sides of the transversal line. These angles are congruent and non-adjacent. In the above diagram, alternative interior angles are 4,5 and 3,6.

Alternate exterior angles; Refer to two angles located on the exterior side of the parallel lines and alternative sides of the transversal line. Like alternative interior angles, the alternative exterior angles are congruent and non-adjacent. From the diagram above, the alternative exterior angles are 1,8 and 2,7.

Corresponding angles: These are two angles; one may be interior and the other exterior, but they are on the same side of the transversal line. Also, these types of angles are non-adjacent and congruent. The examples of corresponding angles from the diagram above may include 1,5; 2,6; 3,7; and 4,8.

Consecutive interior angles; These are interior angles located on the same side of the transversal line. They are also referred to as allied angles or co-interior angles. In the above diagram, consecutive interior angles are 3,5 and 4,6.