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 301
betheir common section :BD shall he a straight line. N B c / E \ C ^ A Construction. If it be not, from B to D, draw in the planeAB the straight line BED, and in the plane BO the straightline BFD. [Postulate L Proof. The two straight lines BED, BED have the sameextremities, and therefore include a… … Proposition 4. Theorem. If a straight line stand at right angles to each of two straightlines at the point of their intersection, it shall also be at right anglesto the plane which passes through them, that is, to the plane inwhich they are. Let the straight liae EF stand at rightangles to each of…
Euclid's Elements · Geometry · Mathematics, Greek
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