Curated OER
Special Triangles and Quadrilaterals
In this special triangles instructional activity, students examine given special triangles. They determine the length of a missing side and/or the measurement of a missing angle for given triangles and quadrilaterals. ...
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...
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.
Cuemath
Cuemath: 30 60 90 Triangle
In this lesson, learn all about the 30-60-90 triangle. Learn about its sides, its area, and the rules that apply to these triangles. Includes simulations and practice questions.
Wolfram Research
Wolfram Mathworld: Isosceles Triangle
MathWorld explains what an isosceles triangle is and how it compares with equilateral, and scalene triangles. The altitude and area of these triangles are also discussed.
Texas Instruments
Texas Instruments: Investigating Special Trangles
This activity will help students visualize the construction of these special triangles and find the ratios of the sides. It will help students later when they being trigonometry. [Requires Adobe Reader.]
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: Triangle Congruence Study Guide
[Free Registration/Login may be required to access all resource tools.] Provides an overview of triangle congruence, including key terms, properties of congruent triangles, triangle postulates and theorems, and special triangles.