Complementary and Supplementary angles are explored in this tutorial video. [9:17] A PowerPoint presentation provides definitions of angle terms and a video offers examples for finding the missing angle in a supplementary or complementary pair. It also includes a link to a matching game for reviewing angle pairs.

Sal uses a protractor to create 10 degrees and 155 degrees angles. [2:41]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

Video explores how to find the measure of angles by adding or subtracting. [1:42]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

Solve two problems that apply properties of tangents to determine if a line is tangent to a circle.

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

Check your skill estimating angles. You can have an error of five degrees.

Students, teachers, and parents alike will enjoy this challenging math site. It contains a clever brain teaser section plus creative problems related to algebra, geometry, measurement, numbers, statistics, and probability. A Spanish version is available.

Demonstrates how to find unknown angles for two intersecting lines when some angle information is given. [3:00]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

The purpose of this task is to give 4th grade students a problem involving an unknown quantity that has a clear visual representation. Students must understand that the four interior angles of a rectangle are all right angles and that right angles have a measure of 90_ and that angle measure is additive.

A structured geometry program teacher edition of daily lesson plans and teacher supports to accompany the College Access Reader: Geometry student edition.

Angles, parallel lines, and transversals are explained through examples and a video lesson. [1:01]

Features a definition and a video lesson on congruent triangles with examples. [1:11]

CK-12 Foundation's Geometry FlexBook is a clear presentation of the essentials of geometry for the high school student. Topics include: Proof, Congruent Triangles, Quadrilaterals, Similarity, Perimeter & Area, Volume, and Transformations.

Explains the basic concept of arcs, angles, and sectors with step-by-step instructions and methods for solving specific problems on your own relating to this topic.

Explains the basic concept of intersecting lines and angles with step-by-step instructions and methods for solving specific problems on your own relating to this topic.

Explains the basic concept of lines and angles with step-by-step instructions and methods for solving specific problems on your own relating to this topic.

Just as rigid motions are used to define congruence in Module 1, so dilations are added to define similarity in Module 2.  To be able to discuss similarity, students must first have a clear understanding of how dilations behave.  This is done in two parts, by studying how dilations yield scale drawings and reasoning why the properties of dilations must be true. Once dilations are clearly established, similarity transformations are defined and length and angle relationships are examined, yielding triangle similarity criteria.  An in-depth look at similarity within right triangles follows, and finally the module ends with a study of right triangle trigonometry.

Find the rest of the EngageNY Mathematics resources at https://archive.org/details/engageny-mathematics.

CK-12's Geometry - Second Edition is a clear presentation of the essentials of geometry for the high school student. Topics include: Proofs, Triangles, Quadrilaterals, Similarity, Perimeter & Area, Volume, and Transformations.

Students learn about geometric relationships by solving real mini putt examples on paper and then using putters and golf balls to experiment with the teacher’s pre-made mini put hole(s) framed by 2 x 4s, comparing their calculated (theoretical) results to real-world results. To “solve the holes,” they find the reflections of angles and then solve for those angles. They do this for 1-, 2- and 3-banked hole-in-one shots. Next, students apply their newly learned skills to design, solve and build their own mini putt holes, also made of 2 x 4s and steel corners.

CK-12 Geometry Teacher's Edition covers tips, common errors, enrichment, differentiated instruction and problem solving for teaching CK-12 Geometry Student Edition. The solution and assessment guides are available upon request.