In the introduction to this site we learn that, "A fundamental result of geometry, used often in secondary and collegiate mathematics, is the equality of ratios of corresponding sides in similar triangles." Accordingly,...

The Geometry Junkyard website provides a broad introduction to the specifics of geometry. The site, designed by David Eppstein of UC-Irvine, provides all the basics of geometry for students and teachers alike. Topics...

In general, a triangle is defined by its three elements. SAS, ASA, and SSS provide three well-known examples but there are many more. Bogomolny provides a table of constructions (linked to constructions) and invites...

A listing, with description and illustration, of 20th-century triangle centers (including: Schiffler Point, Exeter Point, Parry Point, congruent isoscelizers point, Yff Center of Congruence, isoperimetric point and equal...

This geometry lesson from Illuminations presents the Triangle Classification problem. Students will attempt to classify the triangles formed in a plane when a randomly selected point is connected to the endpoints of a...