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: 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: 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: 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.
CPALMS
Cpalms: All Circles Are Similar Especially Circular Pizza!
Chefs at Gaines Street Pies explain how they make their pizzas and why all of their pizzas are similar circles. [4:13]
Sophia Learning
Sophia: Types of Proofs: Lesson 4
This lesson will introduce flow chart proofs, paragraph proofs, and two-column proofs, and explain the similarity and differences between the different types of proofs. It is 4 of 5 in the series titled "Types of Proofs."
Khan Academy
Khan Academy: Proof: All Circles Are Similar
Demonstrates how to use a unit circle on a coordinate grid to prove that all circles are similar. [1:34]