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 263
For fince but (B. 6pr. 2); ■(conft.); (B. 5. pr. 7). Q^E. D. 230 BOOK VI. PROP. XII. PROB. … O find a fourth pro-portional to threegiven lines Draw and take and alfo draw and making any angle; (B. r. pr. 31);is the fourth proportional. bU. (;■. On account of the parallels, (B. 6. pr. 2); •} = { = .} (conft.); ■ ■■•■■■■•« • (B. 5. pr. 7). Q^E. D. BOOK VI. PROP. XIII. PROP. ^31
Euclid's Elements · Geometry
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