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...
Khan Academy
Khan Academy: Triangles: Triangle Angle Example 2
Shows how to find the measure of missing angles using the triangle sum theorem and vertical angles.
Khan Academy
Khan Academy: Geometry: Angles (Part 3)
Identifies and defines the types of angles formed by parallel lines cut by a transversal and the relationship of their measures. Discusses Triangle Sum Theorem. [9:48]