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Alternate Exterior Angles
See It in Action
Two examples of the idea done right—and one common look-alike that is not right.
EXAMPLE
EXAMPLE
NON-EXAMPLE
Definition
Alternate exterior angles are a pair of angles formed when a transversal crosses two lines, and they are:
On opposite sides of the transversal
Outside the two lines
Key fact:
If the two lines are parallel, then alternate exterior angles are congruent (equal in measure).
Example:
If line l and line m are parallel, and transversal t crosses them, then angle 1 and angle 2 form a pair of alternate exterior angles — and they are congruent.
Video
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