Altitude in geometry (also known as height) refers to a segment that extends from any vertex of a triangle and is perpendicular to the line found on the opposite side. This term is also employed to refer to the length of this segment.
There are three theorems that are concerned with heights in geometry. The first one states that the lines containing the altitudes always intersect at a point. The second theorem asserts that an altitude splits a right angle triangle into two similar triangles if one draws it from the right angle to the hypotenuse. The last states that comparable triangles have altitudes whose lengths are equal to the corresponding sides of the similar triangle. A triangle has three altitudes that are concurrent and intersect at the orthocenter.