The circumcircle of the Johnson triangle Δ J_A J_B J_C has center at the orthocenter H of the reference triangle and radius R, where R is the circumradius of the reference triangle. It is therefore congruent both to the circumcircle of Δ A B C and to the Johnson circles. It has circle function l = - (R^2 sin(3A))/(2Δ), where Δ is the area of the reference triangle. It passes through Kimberling center X_265, which is the reflection of the circumcenter X_3 in the Jerabek center X_125.

Johnson circles | Johnson circumconic | Johnson's theorem | Johnson triangle