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 150
F a rig/it line ^■■■■ii—■be a tangent to a circle,and frotn the point of con-tact a right line be drawn cutting the circle, the angle jg^ made by this line with the tangent is equal to the angle ^^ in the alter-ate fegment of the circle. … 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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