Sophia Learning
Sophia: Similarity
This learning tutorial describes the characteristics of similar figures and how to use scale factor and proportions to determine missing side lengths. The lesson includes PowerPoint presentations and videos demonstrating how to solve...
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...
Texas Instruments
Texas Instruments: Dilations in the Plane (Transformations)
In this activity, students will explore the properties of dilations and the relationships between the original and image figures.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Determining Triangle Similarity
Dr. Math responds to a question about how to determine if two triangles are similar. The Dr. goes into detail about the process and gives several examples that are worked out for you.
Analyze Math
Analyze Math: Similar Triangle Examples
The geometry tutorial investigates similar triangles. Students learn about the definitions and theorems of similar triangles. Topics included are angle-angle, side-side-side, and side-angle-side similarity. The activity has several...
Varsity Tutors
Varsity Tutors: Hotmath: Similar Figures
Find a clear explanation of similar figures. Discusses how they can be transformed through a sequence of rotations, reflections, translations, and dilations. Explanations are supported with illustrated examples.
Science Struck
Science Struck: Similarity Statement in Geometry With Examples
Models how to write a similarity statement about different types of triangles and quadrilaterals.
Math Planet
Math Planet: Algebra 1: Similar Figures
Provides examples that illustrate similar triangles.
Math Planet
Math Planet: Geometry: Similarity: Polygons
Provides an explanation, examples, and a video lesson all related to similar polygons. [0:54]
Khan Academy
Khan Academy: Similarity and Transformations
Given two polygons, try to map one onto the other using angle-preserving transformations, and determine whether they are similar. Transformations are done in "intuitive mode." Students receive immediate feedback and have the opportunity...
Illustrative Mathematics
Illustrative Mathematics: G Co Properties of Congruent Triangles
The goal of this task is to understand how congruence of triangles, defined in terms of rigid motions, relates to the corresponding sides and angles of triangles. Aligns with G-CO.B.7.
Illustrative Mathematics
Illustrative Mathematics: G Co Midpoints of Triangle Sides
The goal of this task is to use similarity transformations to relate two triangles. The triangles are obtained by taking midpoints of two sides of a given triangle. Aligns with HSG-CO.C.10.
Illustrative Mathematics
Illustrative Mathematics: G Co Showing a Triangle Congruence: A Particular Case
Given two congruent triangles, students are asked to analyze the effects of different transformations. Aligns with G-CO.A.5.
Illustrative Mathematics
Illustrative Mathematics: G Srt Similar Triangles
This task works toward establishing the AA criterion for similarity of triangles. Learners are asked to provide a detailed sequence of transformations that moves one of the given triangles onto the other. Aligns with G-SRT.A.3.
Illustrative Mathematics
Illustrative Mathematics: G Srt Similar Triangles
The goal of this task is to examine similarity of triangles from the point of view of proportional sides, showing that this is sufficient to conclude that two triangles are similar. Aligns with HSG-SRT.A.2.
Illustrative Mathematics
Illustrative Mathematics: G Srt Are They Similar?
In this task, students are shown two triangles that appear to be similar, but whose similarity cannot be proven without further information. Students are asked to provide a sequence of similarity transformations that maps one triangle to...
Illustrative Mathematics
Illustrative Mathematics: G Srt Similar Quadrilaterals
The goal of this task is to study if the analog of the AA criterion for similarity of triangles holds for different types of quadrilaterals. Aligns with HSG-SRT.A.2.
CK-12 Foundation
Ck 12: Geometry: Sss Similarity
[Free Registration/Login may be required to access all resource tools.] Use the SSS Similarity Theorem to determine if triangles are similar.
CK-12 Foundation
Ck 12: Geometry: Aa Similarity
[Free Registration/Login may be required to access all resource tools.] Use the AA Similarity Postulate to determine if triangles are similar.
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.
CK-12 Foundation
Ck 12: Geometry: Right Triangle Similarity Study Guide
[Free Registration/Login may be required to access all resource tools.] An overview of altitudes and geometric mean is provided in this study guide.
CK-12 Foundation
Ck 12: Geometry: Dilation
[Free Registration/Login may be required to access all resource tools.] In this lesson students explore geometric dilations. Students examine guided notes, review guided practice, watch instructional videos and attempt practice problems.
CK-12 Foundation
Ck 12: Geometry: Area and Perimeter of Similar Polygons
[Free Registration/Login may be required to access all resource tools.] In this lesson students find the ratios of the perimeters and areas of similar polygons. Students examine guided notes, review guided practice, watch instructional...
CK-12 Foundation
Ck 12: Geometry: Dilation
[Free Registration/Login may be required to access all resource tools.] In this lesson, students learn to dilate a figure. Students examine guided notes, review guided practice, watch instructional videos and attempt practice problems.