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.
CK-12 Foundation
Ck 12: Geometry: Inscribed Similar Triangles
[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to apply similarity to solve for missing information in inscribed right triangles.
Alabama Learning Exchange
Alex: Geometric Mean and Indirect Measurement
In this inquiry-based lesson, students will work in groups to gather measurements needed to approximate the height of a building. Students will discover how geometric mean can be used to find the lengths of missing sides of right...
CK-12 Foundation
Ck 12: Elem Math: Classifying Right Obtuse or Acute by Angle Measure
[Free Registration/Login may be required to access all resource tools.] Students watch a video and attempt practice problems on how to classify triangles based on angle measures.
CK-12 Foundation
Ck 12: Geometry: Angle Measures in Given Triangles
[Free Registration/Login may be required to access all resource tools.] Find the degree measure of an unknown angle in given triangles.
Math Is Fun
Math Is Fun: Interactive Triangles
This is an excellent tool for students to explore how changes in the size of a triangle's sides or angles affect its appearance. Different types of triangles and angles are presented.
Texas Instruments
Texas Instruments: Angle Theorem
Students use the Cabri Geometry II Plus software to investigate the relationship between angle and ratio in a right triangle.
CK-12 Foundation
Ck 12: Elem Math: Classifying All Types of Triangles by Lengths of Sides
[Free Registration/Login may be required to access all resource tools.] Students watch a video overview and attempt practice problems on classifying triangles based on length of sides.
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.