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GeometryGeometry816 views·Updated Jun 8, 2026·2 pages

Proportionality and Similarity Theorems for Triangles: Proof, PDF, Formula, Calculator

The triangle proportionality theoremand similarity concepts form fundamental principles...

1
of 2

<h2>Triangle Proportionality Theorem</h2>
<p>The Triangle Proportionality Theorem states that if a line is parallel to one side of a triang

Page 2: Advanced Proportionality and Similarity Transformations

This page covers additional theorems about proportionality and introduces similarity transformations through dilations. It explains how parallel lines interact with transversals and how angle bisectors create proportional segments.

Definition: A dilation is a transformation that creates a similar figure by multiplying all distances from a center point by a scale factor k.

Example: When dilating point (x,y) with respect to the origin, the new coordinates become (kx, ky), where k is the scale factor.

Highlight: For dilations, if 0 < k < 1, the result is a reduction, while k > 1 produces an enlargement.

Vocabulary: A transversal is a line that intersects two or more other lines, while parallel lines are lines that never intersect.

Quote: "If three parallel lines intersect two transversals, then they divide the transversals proportionally."

2
of 2

<h2>Triangle Proportionality Theorem</h2>
<p>The Triangle Proportionality Theorem states that if a line is parallel to one side of a triang

Page 1: Fundamental Triangle Similarity Theorems

This page introduces three crucial theorems related to triangle similarity and proportionality. The SAS similarity theorem establishes that two triangles are similar when they share a congruent angle and the sides including that angle are proportional.

Definition: The triangle proportionality theorem states that when a line parallel to one side of a triangle intersects the other two sides, it divides those sides proportionally.

Example: If line segment RT is parallel to side QS in triangle PQS, then PR/PQ = RT/QS.

Highlight: The converse of the triangle proportionality theorem proves that if a line divides two sides of a triangle proportionally, then it must be parallel to the third side.

Vocabulary: Congruent angles are angles that have the same measure, while proportional sides maintain equal ratios.

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GeometryGeometry816 views·Updated Jun 8, 2026·2 pages

Proportionality and Similarity Theorems for Triangles: Proof, PDF, Formula, Calculator

The triangle proportionality theorem and similarity concepts form fundamental principles in geometry, explaining relationships between parallel lines, triangles, and their proportional segments. These theorems provide essential tools for solving geometric problems involving similar triangles and proportional relationships.

Key points:

  • The ...
1
of 2

<h2>Triangle Proportionality Theorem</h2>
<p>The Triangle Proportionality Theorem states that if a line is parallel to one side of a triang

Sign up to see the content. It's free!

  • Access to all documents
  • Improve your grades
  • Join milions of students

Page 2: Advanced Proportionality and Similarity Transformations

This page covers additional theorems about proportionality and introduces similarity transformations through dilations. It explains how parallel lines interact with transversals and how angle bisectors create proportional segments.

Definition: A dilation is a transformation that creates a similar figure by multiplying all distances from a center point by a scale factor k.

Example: When dilating point (x,y) with respect to the origin, the new coordinates become (kx, ky), where k is the scale factor.

Highlight: For dilations, if 0 < k < 1, the result is a reduction, while k > 1 produces an enlargement.

Vocabulary: A transversal is a line that intersects two or more other lines, while parallel lines are lines that never intersect.

Quote: "If three parallel lines intersect two transversals, then they divide the transversals proportionally."

2
of 2

<h2>Triangle Proportionality Theorem</h2>
<p>The Triangle Proportionality Theorem states that if a line is parallel to one side of a triang

Sign up to see the content. It's free!

  • Access to all documents
  • Improve your grades
  • Join milions of students

Page 1: Fundamental Triangle Similarity Theorems

This page introduces three crucial theorems related to triangle similarity and proportionality. The SAS similarity theorem establishes that two triangles are similar when they share a congruent angle and the sides including that angle are proportional.

Definition: The triangle proportionality theorem states that when a line parallel to one side of a triangle intersects the other two sides, it divides those sides proportionally.

Example: If line segment RT is parallel to side QS in triangle PQS, then PR/PQ = RT/QS.

Highlight: The converse of the triangle proportionality theorem proves that if a line divides two sides of a triangle proportionally, then it must be parallel to the third side.

Vocabulary: Congruent angles are angles that have the same measure, while proportional sides maintain equal ratios.

We thought you’d never ask...

What is the Knowunity AI companion?

Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.

Where can I download the Knowunity app?

You can download the app in the Google Play Store and in the Apple App Store.

Is Knowunity really free of charge?

That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.

Most popular content: Sas (side-angle-side) Similarity Theorem

1

Most popular content in Geometry

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Most popular content

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AP US HistoryAP US History

Origins and Dynamics of the Columbian Exchange

Analyze the ecological and economic motivations behind the initial transfer of goods, people, and diseases between the Old and New Worlds.

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Analyze the initial social and religious encounters between Europeans, Africans, and Indigenous peoples in the colonial Americas.

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Origins of Ancient River Civilizations

Analyze the environmental factors and technological innovations that led to the rise of early states in Mesopotamia, Egypt, and the Indus Valley.

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Motivations for European Exploration

Analyze the economic, religious, and political factors that drove European powers to the Americas during the 15th and 16th centuries.

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Foundations of Ethical Guidelines in Research

Practice the core principles of the APA ethical code including informed consent, debriefing, and the role of Institutional Review Boards.

9th1,3360
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AP US HistoryAP US History

Introduction to Native American Societies

Examine the diverse social, political, and economic structures of North American indigenous groups prior to European contact.

9th1,1100
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AP BiologyAP Biology

Introduction to Biological Elements of Life

Practice identifying the essential elements including carbon, nitrogen, phosphorus, and sulfur that compose biological macromolecules.

9th1,7390
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AP US HistoryAP US History

Introduction to the Spanish Encomienda System

Explore the fundamental economic and social structures of the Spanish colonial system, focusing on the encomienda and the casta social hierarchy.

9th8890
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AP World HistoryAP World History

Origins and Continuity of the Byzantine Empire

Analyze the political and cultural transitions from the Roman Empire to the Byzantine Empire, focusing on the reign of Justinian I and his code.

9th1,6320

Can't find what you're looking for? Explore other subjects.

Students love us — and so will you.

4.6/5App Store
4.7/5Google Play

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan SiOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha KlichAndroid user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

AnnaiOS user