Here at the Math Forum, Dr. Math proves the concurrency of the altitudes of a triangle. Links are provided for associated topics.

The student will apply and prove the definition of similar triangles and identify and apply the relationships that exist when an altitude is drawn to the hypotenuse of a right triangle, including the geometric mean.

[Free Registration/Login may be required to access all resource tools.] This concept teaches students properties of altitudes of triangles and how to apply them.

[Free Registration/Login may be required to access all resource tools.] Apply the properties of altitudes.

This site from MathWorld.com offers extensive information on right triangles. The site contains information on numerous characteristics of right triangles, including constructing similar inscribed triangles, altitudes, Pythagorean...

[Free Registration/Login may be required to access all resource tools.] Apply the fact that the altitude of a right triangle creates similar triangles.

Explores triangles and related vocabulary through examples and a video lesson.

This site from Math World describes the altitude of a triangle, and shows how to find these altitudes using the parameter and positions of the vertexes and angles of the triangle. The site gives other interesting formulas involving the...

In this activity, you will construct special segments of a triangle named altitudes, medians, and angle bisectors, Using their definitions. You will look at how an altitude, a median, and an angle bisector divide the area of a triangle....

This resource provides information about the altitude theorem for equilateral triangles, in addition to links on related topics. Requires Java.

Get a visual and animated definition of the altitude(s) of a triangle from LearnAlberta.ca's Mathematics Glossary. [Requires Java.]

[Free Registration/Login Required] Students will use the interactive riangle and points to explore altitudes such as the orthocenter. Click learn more to watch a video and click challenge me to answer a practice question.

In this activity, students use the Cabri Jr. tools to draw altitudes in a triangle. They construct a line perpendicular to a given line and through a given point. [Requires Adobe Reader.]

This activity uses Cabri Jr. to assess the students' knowledge of various segments related to triangles: perpendicular bisector, median, angle bisector, midsegment, and altitude.

The Cabri Jr. Constructions Tools Menu (F3) contains tools for contructing geometric objects. This activity provides practice using several of the tools. The activity also investigates the terms: median of a triangle and the altitude of...

This lesson will demonstrate how to locate the height in an obtuse, right, and acute triangle. It is 2 of 5 in the series titled "Triangle Height."

This lesson will demonstrate how to locate the height in an obtuse, right, and acute triangle. It is 4 of 5 in the series titled "Triangle Height."

MathWorld explains what an isosceles triangle is and how it compares with equilateral, and scalene triangles. The altitude and area of these triangles are also discussed.

Students understand that the orthocenter is the point of concurrence of the three altitudes of a triangle. They construct circumcircles and Feuerbach circles and determine the relationship between them.

[Free Registration/Login Required] In this flipchart, students use the interactive features of Activstudio to understand how to use the properties of perpendicular bisectors, angle bisectors, medians and altitudes of a triangle.

This site contains a wealth of problems that deal with the basic definitions of medians, altitudes, angle bisectors, and perpendicular bisectors or the defining characteristics of the different types of triangles. There are also...

Learn how to construct the bisectors, median and altitude of a triangle.

A list of geometry definitions and a matching activity.

This site provides a definition of what the altitude of a triangle is. It also provides a diagram.