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 160
being the angles ofthe A ACB, are together equal to two right angles ; [I. 32. .*. also the angles ABC, ADC together = two right angles. In the same manner it may be shewn that the angles BAD,BCD are together equal to two right angles. Wherefore, the opposite angles, etc. [q.e.d. 148 EUCLIDS… … B For, let ABCD denote the quadrilateral. Describe a circle roundthe triangle ABC, by IV. 5. Take any point E on the arc cut off byAC and on the same side of AC that D is. Then the angles at B and E together = two right angles, by III. 22,and the angles at B and D together = two right angles, by…
Euclid's Elements · Geometry · Mathematics, Greek
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