Supplementary angles are two angles whose measures add up to exactly 180 degrees. For example, if one angle measures 110 degrees, the other must measure 70 degrees to be supplementary. These angles are often found in various geometric shapes, such as triangles and quadrilaterals, where they can help determine unknown angle measures. In practical applications, supplementary angles can be seen in everyday situations, like when two lines intersect. The angles formed on opposite sides of the intersection are supplementary. Understanding supplementary angles is essential in fields like architecture and engineering, where precise measurements are crucial.