Compass Only
The Strophoid first appears in work by the English mathematician Isaac Barrow in 1670. (Barrow, incidentally, was Isaac Newton’s teacher.) However, Torricelli actually describes the curve in his letters prior to Barrow’s work—around 1645—and Roberval found it as the locus of the focus of the conic obtained when the plane cutting the cone rotates about the tangent at its vertex. The name Strophoid, meaning a "belt with a twist,” was proposed by Montucci in 1846.
The animations presented below are in pairs. The first of the pair is a basic construction that either generates the Strophoid or demonstrates a property of the Strophoid. The second of the pair is an attempt to create an interesting dynamic animation with all of the underlying mathematical construction hidden.
The animations presented below are in pairs. The first of the pair is a basic construction that either generates the Strophoid or demonstrates a property of the Strophoid. The second of the pair is an attempt to create an interesting dynamic animation with all of the underlying mathematical construction hidden.