A Short Tour of Triangle Geometry

Around the Nine-point Circle

Paul Yiu

Department of Mathematics

Florida Atlantic University

April 14, 2007

- Nine-point
circle and Euler line
- Incircle and excircles
- Some
interesting triads of circles

- Fermat points and Napoleon theorem

- Inscribed equilateral triangles
- Reflections and isogonal
conjugates
- Simson line
theorem and line of reflections
- Triangle of
reflections