Elements of geometry : containing the first six books of Euclid, with a supplement on the quadrature of the circle, and the geometry of solids : to which are added, Elements of plane and spherical geometry (1826)
Playfair, John, 1748-1819, Euclid · Philadelphia : Marot & Walter · leaf 153
AC is a diameter, let DE be per=>pendicular to the diameter AC, >ind let AB meet DE in F: the rect-angle BA,AF is equal to the rectangle CA.AD. Join BC, and be-cause ABC is an angle in a semicircle, it is a right angle (31. 3.) ;Now, the angle ADF is also a right angle (Hyp.); and the… … equal to the rectangle ACAD contained by the means (16. 6.^ It*therefore, &c. Q. E. D. PROP. H. THEOR. The perpendiculars drawn from the three angles of anytriangle to the opposite sides intersect one another in thesame point. Let ABC be a triangle,BD and CE two perpendiculars intersect-ing one…
Euclid's Elements · Geometry · Trigonometry
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