scalenetriangleadjacentanglesEquilateralTriangleExteriorAngleTransversalpointsegmentbisectorcorrespond-dinganglesIsoscelesTrianglerightangleSum ofTriangle'sInteriorAnglesAlternateInteriorAnglescongruentanglesstraightangleInteriorAnglesAddsup to90°Addsup to180°parallellinesVerticalAngleslinesegment