The Thirteen Books of Euclid's Elements

area a medial base binomial straight line bisected breadth circle ABCD circle EFGH commensurable in length commensurable in square cone cut in extreme cylinder decagon diameter dodecahedron equilateral Euclid extreme and mean greater segment height icosahedron inscribed irrational straight line kp² Lemma let the square magnitudes mean ratio measure medial area medial straight line medial whole parallelepipedal solids parallelogram pentagon perpendicular plane of reference polygon prism PROPOSITION proved ratio triplicate rational and incommensurable rational area rational straight line rectangle AC rectangle contained right angles second apotome side Similarly solid angle sphere square number square on AB squares on AC straight lines commensurable surable triangle twice the rectangle vertex whence