Khan Academy
Khan Academy: Trigonometric Ratios in Right Triangles
Learn how to find the sine, cosine, and tangent of angles in right triangles.
Khan Academy
Khan Academy: Solving for a Side in Right Triangles With Trigonometry
Learn how to use trig functions to find an unknown side length in a right triangle.
McGraw Hill
Glencoe Mathematics: Online Study Tools: Self Check Quiz on Right Triangles
The online assessment demonstrates knowledge of concepts utilized in Geometry. The multiple choice questions test students on right triangles and trigonometry.
CK-12 Foundation
Ck 12: Geometry: Hl Triangle Congruence
[Free Registration/Login may be required to access all resource tools.] In this lesson students prove two right triangles are congruent with the Hypotenuse-Leg shortcut. Students examine guided notes, review guided practice, watch...
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.
CK-12 Foundation
Ck 12: Elem Math: Determine Unknown Angles: Isosceles, Scalene, Right Triangles
[Free Registration/Login may be required to access all resource tools.] Students watch a video and attempt practice problems on finding the missing angles in triangles.
Khan Academy
Khan Academy: Solve for a Side in Right Triangles
Given one side length and an acute angle in a right triangle, find another side using trigonometry. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Use Pythagorean Theorem to Find Right Triangle Side Lengths
Find the length of the hypotenuse or a leg of a right triangle using the Pythagorean Theorem. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.
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...
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...
Oswego City School District
Regents Exam Prep Center: Geometry Vocabulary Resources
A list of geometry definitions and a matching activity.
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...
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.
CK-12 Foundation
Ck 12: Geometry: 30 60 90 Right Triangles Problem Solving
[Free Registration/Login may be required to access all resource tools.] Identify special triangles and use the characteristics of 30-60-90 triangles in problem solving.
Analyze Math
Analyze Math: Free Math Tutorials: Triangles
The geometry tutorial investigates the definitions and properties of triangles. Topics included are isosceles, equilateral, and right triangles. In addition, the sine and cosine laws of triangles are defined.
CK-12 Foundation
Ck 12: Relationships of Sides in 30 60 90 Right Triangles
[Free Registration/Login may be required to access all resource tools.] Define a 30-60-90 triangle and the relationship between its sides.
Khan Academy
Khan Academy: Special Right Triangles
Use your knowledge of 30-60-90 and 45-45-90 triangles to solve some problems. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
CK-12 Foundation
Ck 12: Geometry: Inscribed Similar Triangles
[Free Registration/Login may be required to access all resource tools.] Apply the fact that the altitude of a right triangle creates similar triangles.
CK-12 Foundation
Ck 12: 45 45 90 Triangles
[Free Registration/Login Required] Students use a baseball field to determine the distance between points and 45-45-90 triangles. Click learn more to watch a video and click challenge me to answer a practice question.
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.
Calculator Soup
Calculator Soup: Right Triangles Calculator
Use this calculator to find the unknown angles in a right triangle using the Pythagorean Theorem. Once you know the sides you can calculate the perimeter, semiperimeter, area, and the altitudes.
CK-12 Foundation
Ck 12: Interactive Geometry: 17.4 Inverse Trigonometric Ratios
Define the trigonometric ratios in terms of ratios of the sides of a right triangle.
CK-12 Foundation
Ck 12: Trigonometry:lengths of Triangle Sides Using the Pythagorean
[Free Registration/Login may be required to access all resource tools.] Find the length of sides of right triangles using the Pythagorean Theorem.
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 plan. (To access this lesson plan, you must register with Crayola.com....