Alternate Exterior Angles | Theorem

Alternate Exterior Angles Definition
Alternate exterior angles are created when three lines intersect. A line that crosses two or more other lines is called a transversal. Often, two of the lines will be parallel, setting up some interesting angles with the transversal.
Video Summary
Now that you have gone through this lesson carefully, you are able to recall that angles on opposite sides of a transversal and outside two lines are called alternate exterior angles. When lines crossed by the transversal are parallel, you can use the Alternate Exterior Angles Theorem to know the alternate exterior angles are congruent. You can now solve problems identifying and measuring alternate exterior angles.
Geometry is a bit like a magician's trick. It sets up some odd event, like parallel lines being crossed by a transversal, and then hopes you're astounded when that improbable event leads to something new, like alternate exterior angles. Even when the lines are not parallel, alternate exterior angles exist, and we don't need to pull a rabbit out of a hat to amaze you with them.