Khan Academy
Khan Academy: Geometry: Ca Geometry: Proof by Contradiction
Demonstrates solutions to problems #4-6 of California Geometry released state test questions. Problems address understanding of proof by contradiction and proving triangles congruent. [11:56]
Khan Academy
Khan Academy: Geometry: Ca Geometry: Deductive Reasoning
Demonstrates solutions to problems #1-3 of California Geometry released state test questions. Problems address understanding of deductive reasoning and congruent angles created by parallel lines cut by a transversal. [10:17]
Khan Academy
Khan Academy: Geometry: Congruent Triangle Proof Example
Demonstrates how to use triangle congruency to prove that a given point is the midpoint of a given line segment. The proof is written in the form of a two-column proof. Practice problems available. [5:46]
Khan Academy
Khan Academy: Geometry: Ca Geometry: More Proofs
Demonstrates solutions to problems #7-10 of California Geometry released state test questions. Problems address understanding of congruent angle pairs when parallel lines are cut by a transversal, counterexamples, and properties of the...
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: Congruent Triangle Example 2
Demonstrates how to use triangle congruency to prove that corresponding sides of congruent triangles are congruent and then identifies other congruent parts in the overlapping triangle diagram. The proof is written in the form of a...
Khan Academy
Khan Academy: Triangles: Fill in the Blank Triangle Proofs Example 2
This video will fill in the blanks in a proof showing that the triangles are congruent.
Khan Academy
Khan Academy: Two Column Proof Showing Segments Are Perpendicular
Using triangle congruency postulates to show that two intersecting segments are perpendicular
Khan Academy
Khan Academy: Sss to Show a Radius Is Perpendicular to a Chord That It Bisects
More on the difference between a theorem and axiom. Proving a cool result using SSS.
Khan Academy
Khan Academy: Angles: Angle Bisector Theorem Proof
Explanation and proof of the Angle Bisector Theorem.
Khan Academy
Khan Academy: Worked Examples: Geometry: Ca Geometry: Proof by Contradiction
Students explore how to do a geometric proof by contradiction.
Sophia Learning
Sophia: Intermediate Proof
Use the two-column proof and the flow proof to prove two triangles congruent.
Sophia Learning
Sophia: Introduction to Geometric Proof
Explore the structure and how to complete a flow proof and a two-column proof.
Sophia Learning
Sophia: Types of Proofs
Explore the similarities and differences between paragraph proofs, flow chart proofs, and two-column proofs. Assess learning with a quiz.
Khan Academy
Khan Academy: Triangles: Wrong Statements in Proofs Example 1
A video analyzing how to recognize wrong statements in a proof. [2:48]
Khan Academy
Khan Academy: Geometry: Deductive Reasoning
This video explains what is deductive reasoning.
Khan Academy
Khan Academy: Geometry: Angles Formed by Parallel Lines and Transversals
Identifies which angles are congruent when parallel lines are cut by a transversal. [7:07]
