CK-12 Foundation
Ck 12: Triangle Sum Theorem
[Free Registration/Login Required] Students explore the concept of the triangle sum theorem by navigating through the interactive learning module and then answering questions that go along with the module. Students can also learn more...
Math Planet
Math Planet: Geometry: Converse of the Pythagorean Theorem and Special Triangles
The converse of the Pythagorean Theorem is examined through examples and a video lesson. [1:04]
Maths Challenge
Maths challenge.net: Leaning Ladders
Use your right triangle solving skills to solve this ladders in a hole problem.
University of Saskatchewan (Canada)
University of Saskatchewan: Triangles
This site from the University of Saskatchewan provides an explanation of similar triangles, the Pythagorean theorem, and the distance between arbitrary points in a plane. Example problems for each of these concepts are provided.
CK-12 Foundation
Ck 12: Geometry: Triangle Area Grades 6 7
[Free Registration/Login may be required to access all resource tools.] Find the areas of triangles given their base and height dimensions.
CK-12 Foundation
Ck 12: Geometry: Triangle Area Grade 7
[Free Registration/Login may be required to access all resource tools.] Find the area of different triangles given the base and the height.
Khan Academy
Khan Academy: General Triangle Word Problems
Solve word problems that involve general triangles using trigonometry. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Solve Triangles Using the Law of Cosines
Solve missing triangle measures using the law of cosines. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Oswego City School District
Regents Exam Prep Center: Triangle Information
This Oswego City School District site from the Regents Exam Prep Center provides an explanation of the classifications of triangles both by sides and by angles. Pictures are also included.
Texas Instruments
Texas Instruments: Real Life Real World Activity Forestry
Forest industry professionals make measurements in their work using tools including the Clinometer and the Biltmore Stick. These tools are based on the concepts of similar triangles and trigonometric ratios in a right triangle. This...
Analyze Math
Analyze Math: Triangle Problems
Here are five triangle problems to solve using the Law of Sines, Law of Cosines, Pythagorean Theorem, and trigonometry. All problems have detailed written solutions included.
Khan Academy
Khan Academy: Use Pythagorean Theorem to Find Isosceles Triangle Side Lengths
Find the missing side lengths of isosceles triangles by using the Pythagorean Theorem. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.
Khan Academy
Khan Academy: Reciprocal Trig Ratios
Understand the right triangle definition of sec, csc, and cot ratios. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Math Planet
Math Planet: Pre Algebra: Triangles
Learn about the types of triangles by taking a look at an example and a video lesson.
Mangahigh
Mangahigh: Shape: 3 D Trigonometry
Test your knowledge of determing the lengths and angles of right triangles.
CK-12 Foundation
Ck 12: Geometry: Laws of Sines and Cosines
[Free Registration/Login may be required to access all resource tools.] This concept teaches students to find missing sides and angles in non-right triangles using the Laws of Sines and Cosines.
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.
Mangahigh
Mangahigh: Shape: Right Angle in a Semi Circle Rule
Test your knowledge of the measurement of angles in a triangle.
CK-12 Foundation
Ck 12: Geometry: Applications of the Pythagorean Theorem
[Free Registration/Login may be required to access all resource tools.] In this lesson students use the Pythagorean Theorem to find perimeter and area. Students examine guided notes, review guided practice, watch instructional videos and...
CK-12 Foundation
Ck 12: Geometry: Applications of the Pythagorean Theorem
[Free Registration/Login may be required to access all resource tools.] This concept introduces students to several applications of the Pythagorean Theorem. Students examine guided notes, review guided practice, watch instructional...
CK-12 Foundation
Ck 12: Geometry: Inverse Trigonometric Ratios
[Free Registration/Login may be required to access all resource tools.] This concept teaches students to use inverse trigonometric ratios to solve for missing angles in right triangles.
TeachEngineering
Teach Engineering: You've Got Triangles!
Students learn about trigonometry, geometry and measurements while participating in a hands-on interaction with LEGO MINDSTORMS NXT technology. First they review fundamental geometrical and trigonometric concepts. Then, they estimate the...
Khan Academy
Khan Academy: Right Triangle Trigonometry Review
Review right triangle trigonometry and how to use it to solve problems.
Oswego City School District
Regents Exam Prep Center: Pythagorean Theorem
Who was Pythagoras and what is his theorem? Explore this concept and its relationship to the measurement of a right triangle in this test prep lesson plan. The instructional activity includes an interactive worksheet where students...