Khan Academy: Geometry: More on Why Ssa Is Not a Postulate

Explains why SSA is not a valid postulate for proving triangle congruence.

In this video tutorial [11:06], the instructor shows how to construct a two-column proof using triangle congruence postulates to prove that two line segments are perpendicular.

This video tutorial demonstrates solutions to problems #51-55 of the California Geometry released state test questions. Problems address proving and using the Pythagorean theorem and compass constructions. [12:35]

Demonstrates solutions to problems #56-60 of the California Geometry released state test questions. Problems address compass constructions, slope of perpendicular lines, and using the distance formula. [12:49]

Proof that the sum of the angles in a triangle is 180 using the relationship of angles formed when parallel lines are cut by a transversal. This video also appears in the Geometry: Triangles strand. [6:31]

Explains how to determine unknown side lengths of similar triangles by identifying corresponding sides and angles ans setting up proportions. The first example is a continuation from the video "Similar Triangles." Practice problems...

A step-by-step instructional video on how to solve a ratio problem using algebra. [9:58]

Provided are links to Khan Academy content on the following subjects: Computers and the Internet; HTML/CSS; Cryptography; and SOPA/PIPA.

Learning coding in Khan Academy provides video/walk throughs, challenges, and a work project to apply skills learned.

Who would have thought we could use SpongeBob as a mathematical example? A fantastically fun video that provokes higher thinking about the reality that SpongeBob's house might not actually be a pineapple based on its relation to the...