The elements of Euclid : viz, the first six books, together with the eleventh and twelfth : the errors, by which Theon, or others, have long ago vitiated these books, are corrected, and some of Euclid's demonstrations are restored : also, The book of Euclid's data, in like manner corrected (1834)
Euclid, Euclid, Simson, Robert, 1687-1768 · Philadelphia : Desilver & Thomas · leaf 159
iangle. Sec Note. 156 THE ELEMENTS OF EUCLID. BOOK VI. Describe (5. 4.) the circle ACBabout the triangle, and draw its dia-meter AE, and join EC; because theright angle BDA is equal (31. 3.) tothe angle EGA in a semicircle, andthe angle ABD to the angle AEC inthe same segment (21. 3.); the… … PROP. D. THEOR. The rectangle contained by the diagonals of a quad-rilateral inscribed in a circle, is equal to both the rect-angles contained by its opposite sides.* Let ABCD be any quadrilateral inscribed in a circle, and joinAC, BDj the rectangle contained by AC, BD is equal to the tworectangles…
Mathematics, Greek · Geometry · Trigonometry
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