For, if the triangle ABC be applied to the triangle DEF, and if the point B be placed on the point E and the straight line BC on EF, the point C will also coincide with F, because BC is equal to EF.
Coaptato enim ABG trigono super DEZ trigonum, et posito B quidem puncto super E punctum, recta vero BG super EZ, coaptabitur et G punctus super Z eo quod equalis sit recta BG recte EZ.
Probatio: Hoc autem ideo est quia cum triangulus ABG triangulo DEZ superpositus fuerit et basis BG super basim EZ locata fuerit, cadet punctum B super punctum E et punctum G super punctum Z, latera quoque BA; AG cadent super latera ED; DZ,
Rationis causa: Si enim triangulus ABG triangulo HDZ superponatur, punctusque B supra punctum H, lineaque BG supra lineam HZ, punctus G supra punctum Z incidet.
Nam si mente intelligatur basis B C, superponi basi E F, neutra excedet alteram, sed punctum B, congruet puncto E, & punctum C, puncto F, cum hæ bases ponantur æquales inter se.
Title
Book I
