KnowraPerpendicular linesLinked fromLinked fromThe 15 pages that link to Perpendicular lines, each with the reason it gives.All 15Related 10Narrower topic 2Compared with 3OrthocenterNarrower topic: An altitude is defined by perpendicularity to the opposite side’s line.Van Aubel's theoremNarrower topic: Perpendicularity is one of the theorem's two conclusions.