Provides definitions, formulas, and examples relating to the special right triangle, the 30-60-90 degrees.

Explore and measure a variety of triangles.

What better way to get to know your students than with a 1:1 interview. Today you will interview each student on their knowledge of triangles and their ability to separate them from other shapes.

A complete reference guide to congruent triangles. It provides definitions, examples, and an interactive activity that enhances further explanation. Includes links to related topics.

Given two similar triangles and some of their side lengths, find a missing side length.

Demonstrates how to translate, set up, and solve basic right-triangle word problems.

Explains mean proportionals (or geometric means) by providing theorems and examples.

Explore full angles triangles with this handy reference guide. Provides a detailed definition and an interactive activity that enhances further explanation. Includes links to related topics.

Explore reflex angles triangles with this handy reference guide. Provides a detailed definition and an interactive activity that enhances further explanation. Includes links to related topics.

Patterns of numbers don't come along every day, and so when they do, they need to be bragged about! The basic definition of triangular numbers begins this site which also lists many of the properties of these numbers, highlights the...