The elements of Euclid for the use of schools and colleges; comprising the first six books and portions of the eleventh and twelfth books; (1903)
Euclid, Todhunter, I. (Isaac), 1820-1884, ed. edt, Simson, Robert, 1687-1768, ed. edt · London; New York, Macmillan · leaf 46
at least two acute angles ; for if a trianglehad two obtuse angles, their sum would not be less than two rightangles, and this is impossible by the foregoing proposition. T.L.E. 34 EUCLIDS ELEMENTS. Proposition 18. Theorem. If (nie side of a triangle he greater than a second side, the angleopposite… … Construction. Because AC is greater than AB, cut off AD equal to AB, [I. 3. and join BD. Proof. Because ADB is the exterior angle of the triangle BDC, it is greater than the interior opposite angle DCB. [I. 16. But the angle ADB = the angle ABD, [I. 5. because the side AD = the side AB.…
Euclid's Elements · Geometry · Mathematics, Greek
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