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 153
ept FC; .*. FC is perpendicular to DE,Wherefore, if a straight line, etc, [q.e.d. BOOK III. 19. 141 Proposition 19. Theorem. If a straight line touch a circle^ and from the point of contact astraight line he drawn at right angles to the touching line, the centreof the circle shall he in that line.… … Proof. Because DE touches the circle ABC, and FC isdrawn from the centre to the point of contact, FC is perpen-dicular to DE; [III. 18..-. the ^FCE is a right l. But the A. ACE is also a right z.; [Construction,,\ the z.FCE = the Z.ACE, [Axiom \\. that is, the less to the greater, which is…
Euclid's Elements · Geometry · Mathematics, Greek
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