et coniungatur Z, cum get cum D protrahendo lineas ZG, ZD. A puncto quoque Z protrahatur linea recta ZB usque ad arcum GD, quocumque modo cadat, et producatur usque ad punctum E.
ab eadem centro producimus lineas ad G et D. Educamus deinde a media arcu GD rectam lineam in utramque partem a puncta B usque ad notas Z et E.1
1. Hermann seems to follow the figure from his Arabic source, having the point on the arch GD in the middle. However, all our Arabic sources saying that the point is made كيف ما وقع etc.