The Thirteen Books of Euclid's Elements

ABCD apotome applied base binomial straight line breadth called circle commensurable in length commensurable in square common cone construction contained cylinder definition diameter divided double draw drawn equal Euclid figure follows given greater half height Hence incommensurable inscribed irrational straight line joined Lemma less magnitudes measure medial area medial straight line meet parallel parallelepipedal parallelogram pentagon perpendicular plane polygon prism produces proof proportional PROPOSITION proved pyramid rational straight line reference remainder respectively right angles segment side similar Similarly solid sphere square number squares on AC straight lines commensurable Suppose Take third triangle twice the rectangle whence whole