Equal triangles and the axiom of whole and part
Two isosceles triangles compared with dividers; Euclidean common notions
Folio 3r draws two equal isosceles triangles, their vertices lettered a, b, d, c and marked with matching dots, one of them measured off with a pair of dividers. The notes state two Euclidean common notions: that every whole is greater than its part, and that what is neither greater nor lesser is equal. Fainter pencilled triangles and further sketches appear lower on the page and are not transcribed.
On this page
Two equal triangles compared
Two isosceles triangles of equal size are set side by side, lettered a, b, d, c and marked with like dots; one is spanned by a pair of dividers to test the equality of its parts. The captions read partial - total, a - b - c.
Common notions of whole and part
Every whole is greater than its part; and if a thing is neither greater nor lesser than another, then it is equal to it. These are stated as the axioms underlying the comparison of the figures.
Further faint triangle sketches
Below the inked figures are lighter pencilled triangles and a curved line, apparently trial sketches. They carry brief notes that the bundle does not transcribe.