This article is a stub. You can help Math Wiki by expanding it.vte Two angles on a straight line are said to be supplementary. Two angles are supplementary if their measures add up to 180 degrees or π radians. Due to the fact that angles on a straight line sum 180 degrees, angles on straight lines are supplementary. See also Complementary angle Ad blocker interference detected! Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected. Categories: Stubs Geometry Angles Geometry stubs