Find Resources

The purpose of this task is to use similar triangles in order to study the coordinates of points which divide a line segment in a given ratio. These coordinates can be calculated directly but the method employed here not only allows us to find the coordinates of the desired points but also to construct them (with straightedge and compass).

GeoGebra simulation that shows how using a "knotted rubber band" can dilate a triangle.

Slider that shows 2 similar triangles formed by parallel lines and 2 transversals.  The focus is on the vertical angles and the alternate interior angle pairs.

GeoGebra slider that shows a triangle dilation changing as the scale factor changes.

This lesson unit is intended to help you assess how well students are able to solve problems involving area and volume, and in particular, to help you identify and assist students who have difficulties with:
Computing perimeters, areas, and volumes using formulas.
Finding the relationships between perimeters, areas, and volumes of shapes after scaling.

The goal of this task is to apply dilations to a triangle in the coordinate plane. 

The goal of this task is to work on showing that all circles are similar using these two different methods, the first visual and the second algebraic.

A blog about food that focuses on triangular shaped "crescent rolls" that can be cut into smaller size triangles.