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This page is about Adjacent in the context of Angle. For other uses, see Adjacent.


Two angles are adjacent if they have an intersecting line in common:


Also defined as

Some sources give that adjacent angles are the angles on a straight line at the intersection of that line and another.

Under such a definition, $\angle \alpha$ and $\angle \beta$ are adjacent in the diagram below:


Such adjacent angles are seen to be supplementary.