Well, they're called vertically adjacent angles. They have the property that they are supplementary, because the non-adjacent sides form a straight line.
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Where two straight lines cross the "vertically opposite" angles are equal.
Sum of adjacent angles on a straight line.
In a polygon there are no such angles.
Adjacent angles are angles next to each other
they are called supplementary angles. a straight line has 180 degrees each side and two adjacent angles forming 180 degrees are called supplementary angles.