Wolfram Research
Wolfram Math World: Triangles
This site provides detailed overviews of many of the concepts and theorems associated with triangles. Content focuses on general triangles, cevians, triangle centers, triangle circles, and triangle lines.
Cuemath
Cuemath: Median of a Triangle
This lesson explores the equation of the median of a triangle formula, sum of medians of a triangle, altitude of a triangle, median of equilateral triangle formula, and median of a triangle definition while discovering the interesting...
Wolfram Research
Wolfram Math World: Incenter
MathWorld diagrams triangle with its incenter labeled and details how to find the incenter with links to the key terms. The site details many other interesting properties of the triangle incenter.
Other
Antonio Gutierrez: Geometry From the Land of the Incas
Discovering the properties of constructions, seeing proofs in action, and viewing problems come to life here with this wonderful use of technology in the classroom. Single steps are explained and illustrated one at a time so that the...
Other
Center for Technology and Teacher Education:centers of Triangles Lesson Part Two
This is the second of two consecutive lesson plans concerning the centers of a triangle. The lesson requires the use of Geometer's Sketch Pad. The lesson contains real world applications of some of the concurrent points of a triangle.
Math Open Reference
Math Open Reference: Triangles
A complete reference guide to types of triangles and triangle perimeter and area. It provides definitions and interactive animated activities that enhance further explanation.
Math Open Reference
Math Open Reference: Centroid of a Triangle
A complete reference guide to the centroid of a triangle. It provides definitions, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Wolfram Research
Wolfram Math World: Orthocenter
This site from MathWorld provides a diagram of a triangle with its orthocenter labeled. The site details how to find the orthocenter with links to the key terms. The site details many other interesting properties of the triangle...
Other
University of Evansville: Encyclopedia Triangle Centers
This site contains a comprehensive study of triangle centers. Seems more for an advanced level. Provides a list of six links to 1114 centers.
Wolfram Research
Wolfram Math World: Circumcenter
MathWorld diagrams a triangle with its circumcenter labeled and details how to find the circumcenter with links to the key terms.