Source — Euclid's Elements, encoded as an rrxiv paper

X.77 Proposition X.77

If from a straight line there be subtracted a straight line incommensurable in square with the whole which with the whole makes the sum of squares medial but twice the rectangle rational, the remainder is irrational; let it be called that which produces with a rational area a medial whole.

lines 74–74 in main.tex