How to construct an isosceles triangle: Variations of a case added to Euclid's elements, in the medieval Hebrew tradition

In this paper I examine three versions of a case added to Euclid's Elements, Book I, proposition 1, which are found in three late medieval Hebrew texts based on the Elements. The added case explains how to construct an isosceles triangle. Following a brief discussion of this problem and its solutions in the Greek, Arabic, and Latin traditions, I examine the constructions in the Hebrew texts and their peculiarities. In an Appendix I present a partial English translation of the version of this added case found in Ibn al-Haytham's On the Resolution of Doubts on Euclid's Elements.