Khan Academy
Khan Academy: Classifying Triangles
Discusses the different types of triangles and their angles. [6:00]
Khan Academy
Khan Academy: Classifying Triangles by Angles
Explains how to classify a triangle just by knowing the angle sizes. [5:30]
Khan Academy
Khan Academy: Worked Examples: Geometry: Geometry: Triangles and Parallelograms
Students explore the properties of triangles and parallelograms in this video tutorial.
Khan Academy
Khan Academy: Geometry: Euler's Line Proof
Proves that the circumcenter, orthocenter, and centroid all lie on the same line, the Euler line. Proof relies on understanding of properties of similar triangles and properties of special parts of a triangle. [9:50]