Let three equal Circles with centers , , and intersect in a single point and intersect pairwise in the points , , and . Then the Circumcircle of (the so-called Johnson Circle) is congruent to the original three.
See also Circumcircle, Johnson Circle
References
Emch, A. ``Remarks on the Foregoing Circle Theorem.'' Amer. Math. Monthly 23, 162-164, 1916.
Honsberger, R. Mathematical Gems II.
Washington, DC: Math. Assoc. Amer., pp. 18-21, 1976.
Johnson, R. ``A Circle Theorem.'' Amer. Math. Monthly 23, 161-162, 1916.