Khan Academy
Khan Academy: Triangle Similarity Review
Review the triangle similarity criteria and use them to determine similar triangles.
Other
Nearpod: Congruent Triangles & Similarity
In this lesson on congruent triangles, students explore how to use postulates to identify if triangles are congruent by SSS, SAS, ASA, and AAS.
Other
Nearpod: Triangle Congruence
In this lesson, students will prove triangles are congruent using the triangle congruence theorems.
Georgia State University
Georgia State University: Hyper Physics: Law of Cosines
This page from the Georgia State University provides a definition of the Law of Cosines. Also includes a "calculator" to help you find side lengths and opposite angles when you are given either three sides or two sides and a third angle.
AAA Math
Aaa Math: Finding the Third Angle of a Triangle
Finding the third angle of a triangle becomes easier by the explanation and examples presented.
Windstream
Ojk's Precalculus Study Page: The Law of Sines
An introduction to solving acute and obtuse triangles by using the law of sines, including a derivation of the formula. Includes several pictures and examples.
Wolfram Research
Wolfram Math World: Coplanar
This MathWorld site gives the conditions for an object to be coplanar and a good definition of this term. Gives links to related pages.
The Math League
The Math League: Angles and Angle Terms
This resource gives a tutorial on angles with definitions, examples, and pictures.
Math Is Fun
Math Is Fun: Supplementary Angles
Students learn about supplementary angles. A definition, examples, and tips are included.
Math Is Fun
Math Is Fun: Corresponding Angles
Students learn about corresponding angles. A definition and example are included.
The Math League
The Math League: Angles and Angle Terms: Acute Angles
This tutorial provides a basic definition and examples of acute angles.
The Math League
The Math League: Angles and Angle Terms: Angle Bisector
A tutorial on angles with definitions, examples, and pictures.
The Math League
The Math League: Angles and Angle Terms: Complementary Angles
This tutorial provides a short definition of complementary angles.
The Math League
The Math League: Corresponding Angles
This tutorial provides a definition of corresponding angles and additional information is provided on angles.
The Math League
The Math League: Angles and Angle Terms: Right Angle
This tutorial on angles presents a short definition of a right angle.
The Math League
The Math League: Angles and Angle Terms: Supplementary Angles
This tutorial on angles with definitions and examples, provides a definition of supplementary angles. At the top of the page is a series of links for additional information on related subjects.
Sonoma State University
Sonoma State University: Parallel Lines and Similar and Congruent Triangles
This site defines eleven theorems relating to parallel lines and similar and congruent triangles. Links to the theorems and relevant term descriptions are provided.
Other
Mathematics Internet Library: Free Internet Books
Practice problem worksheets are available for students needing to study basic terms relating to triangles and other math concepts.
Other
Ic Teachers: Shapes: Triangles
Are you looking for a very basic website that will explain the basic properties of a triangle? Use this site to learn about the properties of equilateral triangles, isosceles triangles, right triangles,and scalene triangles. There are...
Quia
Quia: Irregular Plurals
Produced by Quia, to allow the user to take an eleven question quiz reviewing different types of angles.
Cut the Knot
Cut the Knot!: The Law of Cosines (Cosine Rule)
This site from Cut The Knot provides an overview of the law of cosines, complete with an explanation of the law and a proof of the law.
ClassFlow
Class Flow: Mystic Rose
[Free Registration/Login Required] In this flipchart, students apply algebraic and geometric sense to create geometric figures including a Mystic Rose.
ClassFlow
Class Flow: Right Triangles
[Free Registration/Login Required] Use this flipchart to help your high school students understand right triangles using the Pythagorean Theorem.
ClassFlow
Class Flow: The Law of Cosines
[Free Registration/Login Required] This flipchart defines and uses the law of cosines to find the missing sides and angles of oblique triangles.