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 278
point D within it draw (12. 11.) the straight line DEat right angles to the plane ABC; in DE take DE, DF equal toone another, upon the opposite sides of the plane, and let G beany point in EF; join DA, DB, DC; EA, EB, EC; FA, FB, FC;GA, GB, GC; because the straight line EDF is at right anglesto the… … angles; therefore the baseEB is equal (4. 1.) to thebase FB; in the same man-ner EA is equal to FA, andEC to FC: and in the trian-gles EBA, FBA, EB, BAare equal to FB, BA; andthe base EA, is equal to thebase FA; wherefore the an-gle EBA is equal (8. 1.) tothe angle FBA, and the tri-angle EBA equal…
Mathematics, Greek · Geometry · Trigonometry
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