The first six books of the elements of Euclid, in which coloured diagrams and symbols are used instead of letters for the greater ease of learners (1847)
Byrne, Oliver, Whittingham, Charles, 1795-1876, Chiswick Press · London : William Pickering · leaf 64
TRAIGHT /mes (_Z) lohich are parallel to the fame Jlratght line ( ), are parallel to one another. … Let interfedl Then, = ^^ = iJB (pr. 29.), (pr. 27.) Q. E. D. 32 BOOK I. PROP. XXXI. PROB.
Euclid's Elements · Geometry
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