Main Page | See live article | Alphabetical index An object is in a vertical position when it is aligned in an "up-down" direction, perpendicular to the horizon. Compare horizontal. A pair of angles are said to be vertical if they share the same vertex and are bounded by the same pair of lines but are opposite to each other. If a pair of angles are vertical, then they are equal (congruent). This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.