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

Explains angles and parallel lines through examples and a video lesson.

Explore the world of transversals in this mini-lesson. Learn about transversals, transversal lines, and angles. There are transversal examples and a few interesting practice questions at the end of the page to strengthen your concepts of...

This site from Advogato is all about angles. It contains information starting with what an angle is and what it looks like, all the way up to bisecting angles and theorems about angles. This is very good information for students just...

Here is a partial list of theorems, postulates, and properties.

This task uses GeoGebra software, which can be freely downloaded, to explore what happens to the line segments and angles of a triangle when it is reflected, rotated, and translated. Includes printable task sheet for students and a...