supplementary anglesSupplementaryAngles2007-10-13 15:58:122007-10-20 15:20:45Definitionangle% this is the default PlanetMath preamble. as your knowledge
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Two angles are called {\em supplementary angles}\, of each other if the sum of their \PMlinkname{measures}{AngleMeasure} is equal to the straight angle $\pi$, \PMlinkname{i.e.}{Ie} $180^\circ$.
For example, when two lines intersect each other, they \PMlinkescapetext{divide} the plane into four disjoint \PMlinkname{domains}{Domain2} corresponding to four convex angles; then any of these angles has a supplementary angle on either side of it (see linear pair). However, two angles that are supplementary to each other do not need to have a common side --- see \PMlinkname{e.g.}{Eg} an entry regarding \PMlinkname{opposing angles in a cyclic quadrilateral}{OpposingAnglesInACyclicQuadrilateralAreSupplementary}.