Merriam-Webster
Merriam Webster: Dictionary Illustration: Types of Triangles
A labeled illustration of six different types of triangles.
Math Is Fun
Math Is Fun: Interactive Triangles
This is an excellent tool for students to explore how changes in the size of a triangle's sides or angles affect its appearance. Different types of triangles and angles are presented.
Math Planet
Math Planet: Pre Algebra: Triangles
Learn about the types of triangles by taking a look at an example and a video lesson.
Oswego City School District
Regents Exam Prep Center: Triangle Information
This Oswego City School District site from the Regents Exam Prep Center provides an explanation of the classifications of triangles both by sides and by angles. Pictures are also included.
Mocomi & Anibrain Digital Technologies
Mocomi: Types of Triangles
Explore the different types of triangles and other properties.
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.
ClassFlow
Class Flow: Classifying Triangles
[Free Registration/Login Required] This lesson covers methods of classifying triangles, both according to the length of their sides and by the measure of their interior angle.
ClassFlow
Class Flow: Understanding Basic Triangles
[Free Registration/Login Required] This lesson presents an introduction to triangles and the methods of identifying them. It includes opportunities for students to interactively identify triangles. It also includes: assessment questions...
Oswego City School District
Regents Exam Prep Center: Geometry Vocabulary Resources
A list of geometry definitions and a matching activity.
Other
Mathematics Internet Library: Free Internet Books
Practice problem worksheets are available for learners needing to study basic terms relating to triangles and other math concepts.
Texas Instruments
Texas Instruments: Try Angle?
In this activity, students investigate properties of triangles by randomly generating possible side lengths for triangles. They learn to determine if three line segments can form a triangle. They also learn to classify triangles as...
The Math League
The Math League: Figures and Polygons
This site provides definitions of different types of polygons and figures.
The Math League
The Math League: Figures and Polygons
This website has basic definitions for most polygons, regular and irregular.