Altitudes of Triangles


An altitude is the segment or line through a vertex that is perpendicular to the opposite side.

Constructing an Altitude

Constructing an Altitude

In the applet above, construct the altitude from point A. Use the geometry tools to construct a line perpendicular to BC through A. --Move the vertices around to make different types of triangles. 1) What do you notice about the altitude? --Construct altitudes through the other two vertices. 2) What do you notice about the three altitudes?


The point of concurrency for the altitudes of a triangle is called the orthocenter.