Virtual Nerd
Virtual Nerd: How Do You Classify Quadrilaterals?
Quadrilaterals are figures with four sides and there are many different types. Watch this tutorial and try to figure out the name for any given quadrilateral. [11:03]
Virtual Nerd
Virtual Nerd: How Do You Identify Corresponding Parts in Congruent Triangles?
Follow along with this tutorial to understand how to identify corresponding sides and angles. [7:31]
Khan Academy
Khan Academy: Geometry: Proof: Opposite Sides of Parallelogram Congruent
Demonstrates how to prove that the opposite sides of a parallelogram are congruent based on knowledge of the special angles created when parallel lines are cut by a transversal and the triangle congruency postulates. [8:30]
Khan Academy
Khan Academy: Geometry: Proof: Opposite Angles of Parallelogram Congruent
This video tutorial demonstrates how to prove that the opposite angles of a parallelogram are congruent based on knowledge of the special angles created when parallel lines are cut by a transversal. [4:08]
Khan Academy
Khan Academy: Geometry: Proof: Diagonals of Parallelogram Bisect Each Other
Demonstrates how to prove that the diagonals of a parallelogram bisect each other based on knowledge of the special angles created when parallel lines are cut by a transversal and the triangle congruency postulates. [9:06]
Khan Academy
Khan Academy: Basic Triangle Proofs Module Example 2
A video proving that the given triangles are congruent by ASA.
Sophia Learning
Sophia: Using Triangles to Examine Quadrilaterals
This lesson demonstrates how to determine properties of quadrilaterals by using triangles.