Khan Academy
Khan Academy: Geometry: Equilateral Triangle Sides and Angles Congruent
In this video tutorial [6:29], the instructor models a proof so show that if the sides of an equilateral triangle are congruent, then all the angles are congruent and vice versa. The instructor uses the knowledge of congruent legs and...
Khan Academy
Khan Academy: Geometry: Equilateral and Isosceles Example Problems
Demonstrates how to use the triangle sum theorem, properties of equilateral and isosceles triangles, and special angle pairs to determine the unknown measures of angles in three different diagrams. [6:27]
Khan Academy
Khan Academy: Geometry: Example Involving Isosceles Triangle and Parallel Lines
Demonstrates how to use the triangle sum theorem, properties of isosceles triangles, and special angle pairs formed when parallel lines are cut by a transversal to set up an equation using given algebraic expressions for angle measures...
Khan Academy
Khan Academy: Geometry: Congruent Parts of Iscosceles Triangles
Proof that if the legs of an isosceles triangle are congruent then the base angles are congruent and vice versa using triangle congruency postulates. The proof is written as a two-column proof. [9:03]
Khan Academy
Khan Academy: Geometry: Another Isosceles Example Problem
Explains how to use given algebraic expressions for the measures of angles in an isosceles triangle and apply knowledge of the triangle sum theorem and the knowledge that the base angles of an isosceles triangle are congruent to...
Virtual Nerd
Virtual Nerd: How Do You Find Missing Angles in an Isosceles Triangle?
Watch this tutorial to learn how identifying a triangle first can be helping in solving for a missing angle measurement. [4:29]
CK-12 Foundation
Ck 12: Elem Math: Overview of Special Triangles
[Free Registration/Login may be required to access all resource tools.] Students watch a video overview on how to find missing angles in triangles.
Khan Academy
Khan Academy: Triangles: Equilateral Triangle Sides and Angles Congruent
A video showing that all of the angles of an equilateral triangle are 60 degrees. The proof is written as a two-column proof.
Sophia Learning
Sophia: Categorizing Triangles With Congruency
In this video tutorial, triangles are classified as isosceles, equilateral, and scalene by the congruency of their sides. Assess learning with a quiz. [1:52]
Sophia Learning
Sophia: Isosceles Triangles
Isosceles triangles are explored in this video tutorial. The lesson models the parts of an isosceles triangle and describes how to find missing angle measures. [5:06]
Sophia Learning
Sophia: Scalene, Isosceles, and Equilateral Triangle
Explore types of triangles including scalene, isosceles, and equilateral in this video tutorial. [3:47] Quiz to follow to check understanding.
Virtual Nerd
Virtual Nerd: Find Missing Angles in an Isosceles Triangle Using Right Triangles
Discover how identifying your triangle first can be very helpful in solving for a missing interior angle measurement. [3:40]
Khan Academy
Khan Academy: Triangles: Another Isosceles Example Problem
Review possible angles for an isosceles triangle in this short video.
Khan Academy
Khan Academy: Example Involving an Isosceles Triangle and Parallel Lines
This video demonstrates how to use the triangle sum theorem, properties of isosceles triangles, and special angle pairs formed when parallel lines are cut by a transversal to set up an equation using given algebraic expressions for angle...
Loyola University Chicago
Math Flix: Isosceles Right Triangle
This QuickTime movie provides an opportunity to learn about the characteristics of the isosceles right triangles. As you watch and listen to the teacher and student interact it helps clarify the thinking behind applying this concept.
Sophia Learning
Sophia: Triangle Exterior Angles Practice
This video lesson demonstrates how to use the triangle exterior angle theorem to find interior angle measurements of a triangle. [4:28]