EntityQ1053976· pop 11· linked from 5 articlesantiparallel lineSign in to saveline antiparallel to another oneConnectionsgeometryEntitytriangleEntityInternational Standard Book NumberEntityangleEntitylineEntityEuclidean vectorEntityconeEntityApollonius of PergaEntityperpendicularityEntitycongruenceEntitycyclic quadrilateralEntityMathWorldEntityaltitudeEntityEric W. WeissteinEntityclockwise directionEntitycevianEntityThomas Little HeathEntitybisectionEntitycircumscribed circle for triangleEntityCategoriesElementary geometry