The Nagel Point and the Extouch Triangle
- Steve Phelps
The Nagel (Na) point is the center of perspective of the triangle and the extouch triangle. The extouch triangle is formed by the points of tangency of the excircles and the sides of the triangle. The isogonal conjugate of the Nagel point (N'a) is the external center of similarity of the circumcircle and the incircle.