Texas Instruments
Texas Instruments: Similar Triangles and Proportions
In this activity, students will investigate the relationship among the similar triangles formed when a segment is constructed parallel to one side of a triangle. They will explore the various ratios that exist between the lengths of the...
Math Open Reference
Math Open Reference: Similar Polygons and Triangles
A complete reference guide to similar triangles and polygons. It provides definitions and interactive activities that enhance further explanation.
Texas Education Agency
Texas Gateway: Similar Right Triangles: The Altitude to the Hypotenuse
The student will apply and prove the definition of similar triangles and identify and apply the relationships that exist when an altitude is drawn to the hypotenuse of a right triangle, including the geometric mean.
Government of Alberta
Learn Alberta: Exploring Similarity and Congruence
Begin by watching this captivating video showing how the concepts of similarity and congruence are found in road signs. Following the video [1:27], an interactive applet allows students to resize, flip, move and rotate triangles to...
Illustrative Mathematics
Illustrative Mathematics: G Gpe, G Srt Finding Triangle Coordinates
Given a picture of a triangle on a coordinate grid, students are asked to find the coordinates of points which divide line segments in a given ratio. Aligns with G-GPE.B.6 and G-SRT.B.5.
CK-12 Foundation
Ck 12: Geometry: Polygon Similarity 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.
Purple Math
Purplemath: Ratios
Explains the basic terminology and formatting of ratios, and demonstrates how to solve typical exercises.
Texas Instruments
Texas Instruments: Math Today Ballooning Inside the Box
In this activity Using the USATODAY infograph, "Ballooning inside the box", students will explore geometric relationships using similar triangles. Identifying triangles with two pairs of congruent angles to explore similarity properties...
Texas Instruments
Texas Instruments: The Tangent Ratio
In this activity students explore the tangent ratio. Students construct a right triangle using perpendicular lines, and a line that forms the hypotenuse of the triangle. When students construct the hypotenuse line it is very important...
ClassFlow
Class Flow: Ratio and Proportion Geometry Review
[Free Registration/Login Required] This flipchart is a Jeopardy style review for Ratio and Proportion. Comes form the McDougal Littell Geometry book.
Illustrative Mathematics
Illustrative Mathematics: A sse.b.4: Triangle Series
The purpose of this task is to emphasize the adjective "geometric" in the "geometric" series, namely, that the algebraic notion of a common ratio between terms corresponds to the geometric notion of a repeated similarity transformation....
Homeschool Math
Homeschool Math: Introduction to Sine
This is an introductory lesson plan about the trigonometric function sine. Young scholars will study several similar right triangles and the ratio of certain two sides in them.
Purple Math
Purplemath: Proportions: Introduction
Explains the basics and terminology of proportions.