An altitude of a geometric figure is a line segment that shows the figure's height. Altitude is also the length of that line segment. Altitude can also be used to mean elevation, or distance above or below sea level.
The altitudes for the geometric figures depicted below are perpendicular to both bases. The altitude of the cylinder is line segment AB, or 1.5 cm.
For a pyramid or cone, the altitude is a line segment from the base to the vertex perpendicular to the base:
A triangle has three altitudes because any one of its sides can be a base. In other words, a triangle can "sit" on any one of its sides. All three altitudes are pictured for the acute triangle. Can you find the remaining two altitudes for the right and obtuse triangles?
Also called height.
See also height.