CK-12 Foundation
Ck 12: Interactive Geometry: 7.8 Triangles in Applied Problems
Explore some problems you can solve with your knowledge of triangles and trigonometry.
CK-12 Foundation
Ck 12: Interactive Geometry: 17.5 Sine to Find the Area of a Triangle
Learn how to sine to find the area of a triangle.
CK-12 Foundation
Ck 12: Interactive Geometry: 4.5 Theorems About Concurrence in Triangles
Find out about some common centers of triangles.
CK-12 Foundation
Ck 12: Interactive Geometry: 4.4 Theorems About Triangles
Discover some theorems about triangles.
PBS
Pbs Learning Media: Triangles: Targeted Math Instruction
Students will learn how to apply the properties and characteristics of all triangles to solve real-world problems and identify and use the unique characteristics of right, isosceles, equilateral, acute, obtuse, and scalene triangles.
Quia
Ixl Learning: Similar Triangles
Brush up on your math skills relating to similar triangles then try some practice problems to test your understanding.
Khan Academy
Khan Academy: Triangle Similarity Review
Review the triangle similarity criteria and use them to determine similar triangles.
Ministry of Education and Employment of Spain
Red Escolar: Un Triangulo Sorprendente
In Spanish. Different activities which involve the following concepts: right triangles, perpendicular lines, classification of triangles, area of a square and Pythagorean theorem.
AAA Math
Aaa Math: Finding the Third Angle of a Triangle
Finding the third angle of a triangle becomes easier by the explanation and examples presented.
Vernet -Virtual Education Resources Network
Salon Hogar: Referencia Rapida De Formulas Geometricas
This site provides the user with a useful reference to different geometric forms, their elements, formulas, and areas. Entirely in Spanish.
Other
Mathematics Internet Library: Free Internet Books
Practice problem worksheets are available for students needing to study basic terms relating to triangles and other math concepts.
ClassFlow
Class Flow: Right Triangles
[Free Registration/Login Required] Use this flipchart to help your high school students understand right triangles using the Pythagorean Theorem.
ClassFlow
Class Flow: The Law of Cosines
[Free Registration/Login Required] This flipchart defines and uses the law of cosines to find the missing sides and angles of oblique triangles.
ClassFlow
Class Flow: Triangles and Angles
[Free Registration/Login Required] Classify angles by their side and angles. Find angles and measure in triangles.
Free Math Help
Free Math Help: Congruent Triangles
Students learn about congruent triangles. The tutorial consists of definitions and sample exercises with solutions.
Free Math Help
Free Math Help: Isosceles Triangles
Students learn about isosceles triangles. The tutorial consists of definitions and sample exercises with solutions.
Free Math Help
Free Math Help: Triangle Inequalities
The lesson investigates the Geometry topic of triangle inequalities. Students learn about the concept and view diagrams and exercises with solutions.
Free Math Help
Free Math Help: Classification of Polygons and Triangles
The Geometry session explores the classification of polygons and triangles. Definitions and examples are included.
Varsity Tutors
Varsity Tutors: Hotmath: Algebra Review: Congruent Triangles
Find a quick, concise explanation of Congruent Triangles. Several examples are given and clearly explained.
ClassFlow
Class Flow: Congruence in Triangles
[Free Registration/Login Required] This lesson helps teach congrence in triangles. Includes practice with postulates, theorems, and logical reasoning.
ClassFlow
Class Flow: Difference of Squares (Algebra)
[Free Registration/Login Required] Pythagorean triples described using a number of triangles. Pythagorean Theorem reinforced using squares and triangles. Assessment built in.
Math Is Fun
Math Is Fun: Triangles Contain 180 Degrees
Students learn about the angle-sum theorem. A definition, example, and proof are included.
Math Is Fun
Math Is Fun: Triangles
Students learn about the terminology and formulas associated with triangles. The learning resource consists of definitions, diagrams, and examples.
Shmoop University
Shmoop: Basic Geometry: Triangles
The geometry resource explores triangles. Descriptions, examples, and practice exercises are included.