Alternate Exterior Angles in Parallel Lines

Alternate Exterior Angles in Parallel Lines

How to solve alternate exterior angles in parallel lines problems: definition, theorem, example, and its solution.

Definition

Alternate Exterior Angles: Definition

By two lines and a transversal,
2 pairs of alternate exterior angles are formed.
(same colored angles)

Theorem

If a transversal passes through parallel lines, then a pair of alternate exterior angles is congruent.

If a transversal passes through parallel lines,
then a pair of alternate exterior angles is congruent.
(= Same colored angles are congruent.)

Example

Find the value of x. The measures of the alternate exterior angles: 8x + 10, 74

These two horizontal lines are parallel.
So the given alternate exterior angles are congruent.

So 8x + 10 = 74.