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Mathematical Treasure: William Braikenridge’s Geometry

Frank J. Swetz (The Pennsylvania State University)

Scottish mathematician William Braikenridge (ca.1700-1762) proved several theorems in Euclidean geometry. Perhaps the most most famous of these theorems was:

If the sides of a polygon are restricted so that they pass through fixed points and all the vertices except one lie on fixed straight lines, the free vertex will describe a conic or a straight line.

He presented this theorem in his Exercitatio geometrica de descriptione linearum curvarum (1733). The title page follows.

The first few pages of the text follow.

These images were obtained through the courtesy of the Max Planck Institute for the History of Mathematics Library. The book may be viewed in its entirety in European Cultural Heritage Online (ECHO).

Index to Mathematical Treasures

Frank J. Swetz (The Pennsylvania State University), "Mathematical Treasure: William Braikenridge’s Geometry," Convergence (June 2017)