in two senses: one sense is that of "corollary", as a result unsought but seen to follow from a theorem. In the other sense, he added nothing to the definition of "the older geometers", except to say that the finding of the center of a circle and the finding of the greatest common measure are porisms.

Pappus on Euclid's porism

Pappus rejected Euclid's definition of porism. A porism, expressed in modern language, asserts that given four straight lines, of which three turn about the points in which they meet the fourth if two of

1.Previous
3.Next