National Council of Teachers of Mathematics
The Math Forum: Problems Library Geometry Triangles
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...
Homeschool Math
Homeschool Math: Area of Parallelograms
This instructional activity presents the idea that the area of any right triangle is exactly half of a certain rectangle, and contains varied exercises for students.
Texas Instruments
Texas Instruments: Simple Constructions
In this skill activity, students can use the Constructions Tools Menu in Cabri Jr. to contruct a parallelogram. They will also construct an altitude, an angle bisector and a median of a triangle.
Louisiana Department of Education
Louisiana Doe: Louisiana Believes: Eureka Math Parent Guide: Area, Surface Area, and Volume Problems
A guide to support parents as they work with their students with area, surface area, and volume problems.
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...
Illustrative Mathematics
Illustrative Mathematics: G Srt Ask the Pilot
In the July 2013 issue of United Airlines' Hemisphere Magazine, a pilot responded to a question about how far in the distance he could see at different altitudes. The solution involved right triangles, lines of tangency to a circle, and...
National Council of Teachers of Mathematics
The Math Forum: Drexel Math Forum: Distance to an Object
Dr. Math offers a way to calculate the altitude of a triangle using only the lengths of the sides of the triangle. He briefly explains how this was used by the Egyptians long ago.
Varsity Tutors
Varsity Tutors: Hotmath: Graphing Calculator Practice: Polygons and Area of Plane Figures
Practice using your graphing calculator for measuring and constructing polygons and other plane figures. If you get stumped or if you would like to check your work, then select the View Solution button, which is located directly under...
Oswego City School District
Regents Exam Prep Center: Concurrence
Find resources for class instruction on concurrence: a lesson on concurrence of medians, altitudes, angle bisectors, and perpendicular bisectors complete with definitions and example diagrams; a six-question practice quiz; and...