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 20
cut (3. I.) off AEto AD; join DE, and upon it describe (l. I.)an equilateral triangle DEF; then join AF;the straight line AF bisects the angle BAC. Because AD is equal to AE, and AF iscommon to the two triangles DAF, EAF;the two sides DA, AF, are equal to the twosides, EA, AF, each to each; and the… … PROP. X. PROB. To bisect a given finite straight line, that is, to di-vide it into two equal parts. Let AB be the given straight line: it is required to divide itinto two equal parts. Describe (l. I.) upon it an equilateral triangle ABC, and bisect(9. 1.) the angle ACB by the straight line CD. AB…
Mathematics, Greek · Geometry · Trigonometry
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