National Council of Teachers of Mathematics
The Math Forum: Triangle Formulas
Investigate the geometric definitions of triangles, focusing upon equilateral, isosceles, right, and scalene with detailed drawings and appropriate formulas for each. This site has links to more information on triangles.
CK-12 Foundation
Ck 12: Elem Math: Determine Unknown Angles: Isosceles, Scalene, Right Triangles
[Free Registration/Login may be required to access all resource tools.] Students watch a video and attempt practice problems on finding the missing angles in triangles.
Oswego City School District
Regents Exam Prep Center: Angles and Triangles
On this site a viewer can learn about the different types of triangles, and categorized by either angles or sides. Tutorials are also included for interior and exterior angles of triangles. A teacher resource page includes a lesson plan...
Beacon Learning Center
Beacon Learning Center: Triangles Side by Side
This comprehensive web lesson describes how to classify triangles by their angle and side measurements. It provides real-world examples and exercises for students to practice the skill.
Crayola
Crayola: Exploring Triangles.
Here's a great geometry activity to display students' knowledge of the different types of triangles. Provides resources and adaptations to supplement this lesson. (To access this lesson plan, you must register with Crayola.com....
CK-12 Foundation
Ck 12: Elem Math: Classifying All Types of Triangles by Lengths of Sides
[Free Registration/Login may be required to access all resource tools.] Students watch a video overview and attempt practice problems on classifying triangles based on length of sides.
CK-12 Foundation
Ck 12: Elem Math: Classifying Triangles by Identifying the Number of Equal Sides
[Free Registration/Login may be required to access all resource tools.] Students watch a video overview and attempt practice problems on classifying triangles based on the number of equal sides.
CK-12 Foundation
Ck 12: Elem Math: Classify Triangles, Composite Figures Number of Equal Sides
[Free Registration/Login may be required to access all resource tools.] Students watch a video overview and attempt practice problems on classifying a triangle inside a composite figure.
CK-12 Foundation
Ck 12: Geometry: Triangle Classification by Side Lengths
[Free Registration/Login may be required to access all resource tools.] Classify different types of triangles by their side lengths.
CK-12 Foundation
Ck 12: Elem Math: Determining the Length of an Unknown Side of a Triangle
[Free Registration/Login may be required to access all resource tools.] Students watch a video tutorial and attempt practice problems on how to determine the unknown side length of a triangle.
Quia
Ixl Learning: Types of Triangles
Brush up on your math skills relating to the types of triangles then try some practice problems to test your understanding.
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 Open Reference
Math Open Reference: Triangle Quiz
Students are assessed on different types of triangles. Definitions of the triangles are included.
McGraw Hill
Glencoe Mathematics: Online Study Tools: Triangles and Angles
This site gives a short interactive quiz which allows students to self-assess their understanding of the concept of triangles and angles.
AAA Math
Aaa Math: Types of Triangles Based on Sides
Students can practice classifying triangles based on side lengths through a series of self-check exercises and timed learning games.
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.
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...
Merriam-Webster
Merriam Webster: Dictionary Illustration: Types of Triangles
A labeled illustration of six different types of triangles.
Other
Ic Teachers: Shapes: Triangles
Are you looking for a very basic website that will explain the basic properties of a triangle? Use this site to learn about the properties of equilateral triangles, isosceles triangles, right triangles,and scalene triangles. There are...
Wolfram Research
Wolfram Mathworld: Isosceles Triangle
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.
CK-12 Foundation
Ck 12: Elem Math: Classifying Triangles Within Composite Figures
[Free Registration/Login may be required to access all resource tools.] In this learning module, students are presented with a composite figure and must identify the types of triangles within it. An accompanying video demonstrates a...
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.
Math Is Fun
Math Is Fun: Right Angled Triangles
The resource investigates right triangle. Topics explored are isosceles, scalene, and 3,4,5 triangles. Examples, illustrations, and definitions are included.
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...