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 151
If the chord fhould pafs through the centre, it is evi-dent the angles are equal, for each of them is a right angle.(B. 3. prs. 16, 31.) But if not, draV from the point of contadl, it muft pafs through the centre of thecircle, (B. 3. pr. 19.) .-. ^ = ^ (B.3.pr.3i.) W + f =• CA = f (B- I- pr. 32.)/.…
Euclid's Elements · Geometry
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