National Council of Teachers of Mathematics
The Math Forum: Analytic Geometry Formulas
This site from The Math Forum defines and explains, with examples, analytic geometry. Content includes a focus on one, two, and three dimension analytic geometry. Links are also provided for additional information.
Sonoma State University
Sonoma State University: Parallel Lines and Similar and Congruent Triangles
This site defines eleven theorems relating to parallel lines and similar and congruent triangles. Links to the theorems and relevant term descriptions are provided.