Rectangle cut by its diagonal, with two complements
A parallelogram crossed by two parallelograms about the diagonal, leaving two complements
A faint pencil diagram shows a rectangular parallelogram divided by its diagonal, with two smaller parallelograms straddling that diagonal and the two remaining regions, which the caption calls the 'complements', left on either side. It treats the equality of these complementary areas about the diameter of a parallelogram, part of the notebook's geometry after Euclid. A 'Bibliotheque de l'Institut' stamp is impressed at lower right, and no running text was transcribed for this page.
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Rectangle divided by a diagonal, with two complements
A rectangular parallelogram is cut by its diagonal; two parallelograms lie across the diagonal, and the two regions left on either side are the 'complements' named in the caption. The figure concerns the equality of these complementary areas about the diameter.