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On a Theorem in Geometry
Year of Award: 1968
Publication Information: The American Mathematical Monthly, vol. 74, 1967, pp. 627-640
Summary: The theorem under discussion is, "If four circles in a plane touch each other externally, and if r1, r2, r3, and r4 denote their curvatures (that is the reciprocals of their radii), then the following relation holds:
2(r12 + r22 + r32 + r42) = (r1 + r2 + r3 + r4)2."
About the Author: (from The American Mathematical Monthly, vol. 74, (1967)) Daniel Pedoe was at the University of Minnesota at the time of publication.