Alternate Exterior Angles

When two lines are crossed by another line (called the Transversal):

The pairs of angles on opposite sides of the transversal but outside the two lines are called Alternate Exterior Angles.

In the example:

(To help you remember: the angle pairs are on "Alternate" sides of the Transversal, and they are on the "Exterior" of the two crossed lines)

Parallel Lines

When the two lines being crossed are Parallel Lines the Alternate Exterior Angles are equal.

(Click on "Alternate Exterior Angles" to have them highlighted for you.)