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 178
isa right angle, therefore AD+DE=AE3, andADE is therefore a (48. 1.) right angle. There-fore ED is perpendicular to the three lines BD,Da, DC, whence these lines are in one plane(5. 2. Sup.). But AB is in the plane in whichare BD, DA, because any three straight lines,which meet one another, are in… … PROP. VII. THEOR. If two straight lines be parallel, and one of them at rightangles to a plane j the other is also at right angles to thesame plane. Let AB, CD be two parallel straight lines, and let one of them ABbe at right angles to a plane; theother CD is at right angles to thesame plane. For,…
Euclid's Elements · Geometry · Trigonometry
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![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-67-45.webp)
