Khan Academy: Geometry: Identifying Rays

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...

Shows how to identify complementary and supplementary angles in a diagram. [2:36]

Identifying parallel and perpendicular lines in a diagram. [3:34]

Explains terms and notation of basic elements of geometry. [12:57]

Introduction to Euclid, Euclid's Elements, and Euclidean geometry. [8:23]

Demonstrates how to solve five different problems from a released California Geometry state test that involve finding the measures of angles in different polygons. This video also appears in the Geometry: Worked Examples section. [10:58]

Demonstrates solutions to problems #76-80 of California Geometry released state test questions. Problems address tangents to circles, secants to circles, intercepted arcs, translations on the coordinate plane, and rotations on the...