Experiments with triangular paper cut-outs; Euclidean notions
Overlapping triangular cards illustrating equality of figures
The folio records experimental combinations of triangular pieces of paper, arranged and overlapped in many cases. Captions invoke Euclidean common notions: "Conclusion" is written beneath the first figure and, beneath the second, the principle that if equal parts are removed from equal things the remainders stay equal. In a fifth figure equal angles are marked with the labels a and o. The exercise demonstrates equality of figures by superposition.
On this page
Conclusion beneath the first triangular figure
The first arrangement of triangular cards is closed with the single word "Conclusion," marking the result drawn from the superposition.
Equal parts removed from equal things
Beneath the second figure the note begins the common notion that if equal parts are removed from equal things, the remainders will be equal.
Equal angles labeled a and o
In the fifth figure equal angles are marked within one of the cases and identified by the labels a and o.