A Tour of Triangle Geometry

Steve Phelps, craciun gheorghe, Feb 14, 2015

Inspired by Paul Yiu


  • 1. Orthocenter and Circumcenter are Isogonal
  • 2. The Incenter, Gergonne Point, and Tritangent Circles
  • 3. The Excircles and the Nagel Point
  • 4. The Excircles and the Nagel Point 2
  • 5. The Symmedian Point
  • 6. Constructing Isogonal Conjugates
  • 7. Pedal Circle of Isogonal Conjugates
  • 8. The Orthocenter and CIrcumcenter are Isogonal Conjugates
  • 9. The Nine-Point Circle and the Euler Line
  • 10. The Feuerbach Theorem and the Feuerbach Point
  • 11. The Feuerbach Theorem and the Feuerbach Point Part 2

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Orthocenter and Circumcenter are Isogonal

The classical centers are centroid, the circumcenter, the orthocenter and the incenter. The orthocenter (H) and the circumcenter (O) are shown below. The line AH and AO are isogonal with respect to sides AB and AC. Go ahead and draw lines BH and BO as well as CH and CO. Confirm that they are isogonal.
– Steve Phelps

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