Mathematical and Geometrical
Explorations
of the
Nine-Point Circle



This circle is the first really exciting one to appear in any course on elementary geometry.

Daniel Pedoe [1910- ]


This project focuses entirely on the investigation and exploration of an interesting geometric concept, the Nine-Point Circle. A historical account of the Nine-Point Circle is presented along with mathematical and geometrical explorations and connections to the Nine-Point Circle.


Construction of the Nine-Point Circle and Nine-Point Center


Historical Background of the Nine-Point Circle


The Eight-Point Circle and the Nine-Point Circle:
Mathematical History Overlooked



Properties of the Nine-Point Circle and the Nine-Point Center


Existence of the Nine-Point Circle: A Geometrical Proof


Altitudes, Orthocenters, and the Nine-Point Circle


Pedal Triangles and the Nine-Point Circle


Implications for the Use of Teaching the Nine-Point Circle in a Secondary Mathematics Geometry Class


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