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Same-Side Interior Angles Converse
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
The Same-Side Interior Angles Converse states:
“If two lines are cut by a transversal and the same-side interior angles are supplementary, then the two lines are parallel.”
In other words:
If the two angles on the same side of the transversal and between the two lines add up to 180°,
Then you can conclude that the two lines are parallel.
Also known as:
The Consecutive Angles Converse
Why it matters:
This converse is used to prove that two lines are parallel by checking if the same-side interior angles are supplementary.
Video
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