Learn about similar triangles with this helpful reference tool. Provides a detailed definition, 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.

Review the triangle similarity criteria and use them to determine similar triangles.

[Free Registration/Login may be required to access all resource tools.] Use the AA Similarity Postulate to determine if triangles are similar.

[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to identify whether or not two triangles are similar using AA Similarity.

Learn the many theorems about triangles that you can prove using similar triangles.

[Free Registration/Login may be required to access all resource tools.] An overview of altitudes and geometric mean is provided in this study guide.

[Free Registration/Login may be required to access all resource tools.] This study guide looks at similar polygons, scale factor (ratio), and triangle similarity.

Want to stretch your imagination? One good way is to try to imagine how far it is to a distant star. How much farther away is it than the moon is from the earth? In this project, you'll learn one way of measuring the distance without...

This lesson is an introduction to triangles and trigonometry by looking at the history of mapping and specifically, measuring the height of a mountain.

Looks at the garment factory industry in the 1800s and the early part of the 20th century, where workers toiled in sweatshop conditions. After a terrible fire at the Triangle Shirtwaist Company in 1911, labor unions gained support in...

Eighth graders work with slopes and similar triangles in this problem and will learn why the calculated slope will be the same for any two points on a given line. Aligns with 8.EE.B.6.

Basic exercises are presented to help students understand the concept of the area of triangles and the angles of a triangle.

A computer simulation of viewing through various lengths of tubes at different distances. The simulation also has an exploration of focus questions. [Requires Java.]

The purpose of this lesson is to help students apply math concepts concerning similar triangles and trigonometric functions to real life situations. The students learn how to take these concepts and use them to find measurements of...

How would you design the seating for an Olympic stadium to give spectators the best view of events? This geometry and modelling activity is designed to be accessible to both GCSE and A-level maths students (Key Stage 4 and Key Stage 5),...

[Free Registration/Login may be required to access all resource tools.] This study guide looks at the definitions and units for perimeter, area, and circumference, and at the perimeter and area of different shapes, including regular...

This is an introductory lesson about the trigonometric function sine. Students will study several similar right triangles and the ratio of certain two sides in them.