Beacon Learning Center
Beacon Learning Center: Triangles Side by Side
This comprehensive web lesson describes how to classify triangles by their angle and side measurements. It provides real-world examples and exercises for students to practice the skill.
Maths Challenge
Maths challenge.net: Leaning Ladders
Use your right triangle solving skills to solve this ladders in a hole problem.
Maths Challenge
Maths challenge.net: Right Triangle Equal Parts
A geometry proof problem involving a right triangle and finding angles of equal measure.
University of Saskatchewan (Canada)
University of Saskatchewan: Geometry
The University of Saskatchewan's Department of Mathematics and Statistics provides high school students with online tutorials and exercises on what they deem some of the most important topics in geometry: Triangles, and Circles and Other...
Maths Challenge
Maths challenge.net: Right Angle Reasoning
A geometry problem for students to use their mathematical reasoning skills to explain a right triangle property.
McGraw Hill
Glencoe: Self Check Quizzes the Pythagorean Theorem
Students answer multiple choice questions about the Pythagorean Theorem. The questions questions are self-checking and hints are provided.
National Council of Teachers of Mathematics
Nctm: Illuminations: Proof Without Words: Pythagorean Theorem
Students use this computer applet to visualize the Pythagorean Theorem.
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Right Triangles and Trigonometry
Twenty-five problems cover the topic of right triangles and trigonometry in different settings. They are given with each step to the solution cleverly revealed one at a time. You can work each step of the problem then click the "View...
TeachEngineering
Teach Engineering: Trigonometry via Mobile Device
Students investigate the relationships between angles and side lengths in right triangles with the help of materials found in the classroom and a mobile device.
TeachEngineering
Teach Engineering: Handheld Trigonometry
In addition to understanding the concept of similar right triangles and how they apply to trigonometric ratios, students explore a clinometer app, and discover how it can be used to test the mathematics underpinning trigonometry.
Crayola
Crayola: Exploring Triangles.
Here's a great geometry activity to display students' knowledge of the different types of triangles. Provides resources and adaptations to supplement this lesson. (To access this lesson plan, you must register with Crayola.com....
National Council of Teachers of Mathematics
The Math Forum: Triangle Formulas
Investigate the geometric definitions of triangles, focusing upon equilateral, isosceles, right, and scalene with detailed drawings and appropriate formulas for each. This site has links to more information on triangles.
Oswego City School District
Regents Exam Prep Center: Angles and Triangles
On this site a viewer can learn about the different types of triangles, and categorized by either angles or sides. Tutorials are also included for interior and exterior angles of triangles. A teacher resource page includes a lesson plan...
Oswego City School District
Regents Exam Prep Center: Special Right Triangles
A collection of lessons, practice activities, and a teacher resource that will aid your exploration and understanding of special right triangles.
Oswego City School District
Regents Exam Prep Center: Geometry Vocabulary Resources
A list of geometry definitions and a matching activity.
Mathigon
Mathigon: Geometry: Triangles and Trigonometry: Properties of Triangles
This lesson focuses on the properties of triangles, a closed shape that has three sides, three vertices, and and three internal angles. There are different types of triangles such as a right triangle, obtuse, and acute based on the...
University of Georgia
University of Georgia: Inter Math: Recommended Investigations of the Triangle
Investigate the qualities of a triangle with these seventeen word problems. Many include ways to extend the lesson.
National Council of Teachers of Mathematics
The Math Forum: Geoboard Activities
Math Forum provides a set of links to sites that are related to geoboard activities. There are several great links to lessons using geoboards. The links provide insight into how to use them, including how to perform various measurements...
Cuemath
Cuemath: Right Angled Triangle
Explore and learn about the features and properties of a right triangle in this lesson. Includes examples and practice questions.
Cuemath
Cuemath: Altitude of a Triangle
Explore the world of the altitude of a triangle in this mini-lesson including its definition, altitudes in different types of triangles, formulae, some solved examples, and a few interactive questions for you to test your understanding.
Curated OER
Zona Land: Trigonometry, Right Triangles
This site provides information on sine, cosine, and tangent. Lengths of the sides are discussed and many diagrams/tables are shown.
Curated OER
Zona Land: Right Triangle Solver 1
A java applet that will solve a right triangle when you provide information for angle D and its opposite side d.
AAA Math
Aaa Math: Types of Triangles Based on Angles
Students can practice classifying triangles based on angle measurements through a series of self-check exercises and timed learning games.
Rice University
Rice University: Geometry Online: Impossible Triangles
This site has an activity that displays several impossible triangles. The rules for triangles are also displayed. The student has to determine which rule has been violated for each impossible triangle.