Short Answer 
Alternate exterior angles are angles outside two lines cut by a transversal, positioned on opposite sides. For angle 5, the alternate exterior angles are angle 3, 13, and 9, which help in establishing line relationships; if these angles are congruent, it indicates the lines are parallel.
Step 1: Understanding Alternate Exterior Angles
Alternate exterior angles are pairs of angles that lie outside two lines cut by a transversal and are on opposite sides of this transversal. For example, if angle 5 is located between two lines, the alternate exterior angles can be identified as those not adjacent and located opposite to angle 5. In geometry, recognizing these angles is essential for proving parallel lines.
Step 2: Identifying Alternate Exterior Angles for Angle 5
When you identify angle 5, look for the angles that meet the criteria of being alternate exterior angles. In this case, the angles that are alternate exterior to angle 5 are:
- Angle 3
- Angle 13
- Angle 9
These angles help establish relationships between the lines involved when studied in conjunction with a transversal.
Step 3: Applying the Theorem
The theorem states that if two lines are cut by a transversal and the alternate exterior angles are congruent, then the two lines are parallel. This property is crucial in geometry as it allows us to draw conclusions about the orientation of the lines based on the measurements of the angles. Thus, by observing the angles mentioned, you can determine the nature of the lines they are associated with.