The de Longchamps point L is the reflection of the orthocenter H about the circumcenter O of a triangle. It has triangle center function α = cos A - cos B cos C, and is Kimberling center X_20. As a result of its definition, the de Longchamps point is collinear with the orthocenter H and circumcenter O of a triangle.

anticomplementary triangle | circumcenter | circumcircle | Euler-Gergonne-Soddy triangle | Euler line | GEOS circle | orthic axis | orthocenter | Soddy line