TED Talks
Ted: Ted Ed: Euclid's Puzzling Parallel Postulate
Euclid, known as the "Father of Geometry," developed several of modern geometry's most enduring theorems--but what can we make of his mysterious fifth postulate, the parallel postulate? Jeff Dekofsky shows us how mathematical minds have...
CK-12 Foundation
Ck 12: Geometry: Lines in the Coordinate Plane Study Guide
This study guide on lines in a coordinate plane covers key terms, what different line slopes look like, postulates about parallel and perpendicular lines, the slope-intercept equation, how to graph parallel and perpendicular lines, and...
University of St. Andrews (UK)
University of St. Andrews: Johann Heinrich Lambert
This page, which is provided by the University of St Andrews, offers a short biography on Johann Heinrich Lambert, a French-German mathematician (1728-1777.) It discusses his life and his contributions to mathematics.