Commentary on Proposition IV.8

Back to Proposition IV.8.

[Folio 0101 | p. 95]

As was remarked in the last note, a circle can be inscribed in any quadrilateral which has the sum of one pair of opposite sides equal to the sum of the other pair. In particular, it follows that a circle can be inscribed in a square or a rhombus, but not in a rectangle or a rhomboid.