Curated OER
Indirect Euclidean Proofs
In this indirect Euclidean proof learning exercise, students write statements supporting the reasons for a given proof. This one-page learning exercise contains ten problems.
CK-12 Foundation
Ck 12: Geometry: 30 60 90 Right Triangles
[Free Registration/Login may be required to access all resource tools.] Apply the special properties of 30-60-90 right triangles.
Lawrence Hall of Science
The Math Page: Trigonometry: The 30 60 90 Right Triangle
Here is a site that clearly and thoroughly explains the trigonometry of the 30-60-90 right triangle. There are example problems solved, problems for the student to attempt, and answers to the student problems. Point this site out to...
CK-12 Foundation
Ck 12: Geometry: 30 60 90 Right Triangles Intermediate
[Free Registration/Login may be required to access all resource tools.] This concept teaches students about the 30-60-90 special right triangle and how to apply its properties.
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.
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.
Oswego City School District
Regents Exam Prep Center: Special Right Triangles 30 60 90
This tutorial shows two special formulas that are used to determined the measures of the legs of 30-60-90 triangles. And if you can't remember the formula, the tutorial gives you tips on other methods you can use.
Math Open Reference
Math Open Reference: 30 60 90 Triangle
Learn about the 30-60-90 triangle with this helpful reference tool. Provides a detailed definition, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Purple Math
Purplemath: Special Angle Values: 30 60 90 and 45 45 90 Triangles
Explains a simple pictorial way to remember basic reference angle values. Provides other memory aids for the values of trigonometric ratios for these "special" angle values, based on 30-60-90 triangles and 45-45-90 triangles.
CK-12 Foundation
Ck 12: Geometry: Special Right Triangles Study Guide
[Free Registration/Login may be required to access all resource tools.] Different types of right triangles and trigonometric ratios for special right triangles are covered in this study guide.
Oswego City School District
Regents Exam Prep Center: Special Right Triangles 45, 45, 90
This Oswego City School District Regents Exam Prep tutorial shows two special formulas that are used to determined the measures of the legs of a 45-45-90 triangles. If you can't remember the formula, the tutorial gives you tips on other...
Curated OER
45 45 90 and 30 60 90 Triangles
The formulas for 45-45-90 and 30-60-90 triangles and the use of the Pythagorean theorem to prove the formulas.
Khan Academy
Khan Academy: Special Right Triangles
Use your knowledge of 30-60-90 and 45-45-90 triangles to solve some problems.
Sophia Learning
Sophia: Two Special Triangles: Lesson 5
This lesson explains what 45-45-90 and 30-60-90 right triangles are and discusses their properties. It is 5 of 5 in the series titled "Two Special Triangles."
Sophia Learning
Sophia: Two Special Triangles: Lesson 1
This lesson explains what 45-45-90 and 30-60-90 right triangles are and discusses their properties. It is 1 of 5 in the series titled "Two Special Triangles."
Analyze Math
Analyze Math: Special Triangles Used in Trigonometry
The trigonometry tutorial investigates special triangles. The activity includes isosceles right triangles and 30-60-90 triangles. The examples show how to obtain the six trigonometric ratios of the special angles using special triangles.
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.
Geometry Help
Geometry Help: Right Triangles
Explains the basic concept of right triangles with step-by-step instructions and methods for solving specific problems on your own relating to this topic.
Fun Trivia
Fun Trivia: Right Triangles Trivia Quiz
Take this ten question quiz on right triangles as a review for a quiz or test. After submitting your results, you will get step by step instructions for each problem.
Other
Brown Math: A 10 Minute Trig Review
Looking for a 10-minute review of the major concepts of trigonometry? This site is a quick recap of degrees and radians, SOH CAH TOA, Pythagorean identities, and special right triangles are all found here.
Windstream
Ojk's Precalculus Study Page: Evaluating and Graphing Sine and Cosine
An introduction to graphing the sine and cosine functions by using the 30-60-90 and 45-45-90 right triangle values of the two functions as guides.
Sophia Learning
Sophia: Using Right Triangle Trigonometry to Find the Area of Regular Polygons
This lesson will demonstrate how to use right triangle trigonometry and special right triangles (45-45-90 and 30-60-90) to find the area of triangles given the side lengths of the polygon. It is 2 of 4 in the series titled "Using Right...
Sophia Learning
Sophia: Using Right Triangle Trigonometry to Find the Area of Regular Polygons
This lesson will demonstrate how to use right triangle trigonometry and special right triangles (45-45-90 and 30-60-90) to find the area of triangles given the side lengths of the polygon. It is 4 of 4 in the series titled "Using Right...
Pennsylvania State University
Pennsylvania State Univ.: Trilingual Packaging Dilemma
This site from the Pennsylvania State University provides a hands-on activity to bridge the gap between right triangles, 30-60-90 and 45-45-90 theorems, and trigonometry, and what every student wants to know, "When will I ever use this?"...