An introduction and a guide to trigonometry, with hints and answers to exercises, and Java applets as illustrations. Contents include applications of trigonometry, angle measurement, chords, sines, cosines, tangents and...

A searchable catalogue of hundreds of special triangle points (centroid, incenter, Hofstadter points, Yff centers, Apollonius point, etc.), with a glossary, collinearities, graphics, and links to biographical sketches of...

This geometry lesson from Illuminations presents a real-world problem for students to solve with mathematical functions. The material involves constructing the circumcenter and incenter of a triangle. Learners will gain...

This geometry lesson from Illuminations introduces a hands-on learning activity for students in grades 9-12. The class will use pasta to create models of triangles. They will examine the relationship between sides and...

Created by Bruce and Katherine Cornwell, this film from 1976 includes no narration but still manages to demonstrate a number of geometric properties of a triangle, including incenter and circumcenter, through simple...