The straight line on which all Points at Infinity lie. The line at infinity is given in
terms of Trilinear Coordinates by

which follows from the fact that a Real Triangle will have Positive Area, and therefore that

Instead of the three reflected segments concurring for the Isogonal Conjugate of a point on the Circumcircle of a Triangle, they become parallel (and can be considered to meet at infinity). As varies around the Circumcircle, varies through a line called the line at infinity. Every line is Perpendicular to the line at infinity.

© 1996-9

1999-05-25