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 241
es are at right angles. Let ACBD, AEBF be two great circles, the planes of which are atright angles to one another, the poles of the circle AEBF are in thecircumference ACBD, and the poles of the circle ACBD ia the cir-cumference AEBF. From G the centre of the sphere, draw GC in the plane… … right angles to the plane AEBF,is at right angles to the commonsection of the two planes, it is(Def. 2. 2. Sup.) also at right an-gles to the plane AE BF,and there-fore (Cor. 1. 3.) C is the pole ofthe circle AEBF; and if CG beproduced to D, D is the other poleof the circle AEBF. In the same…
Euclid's Elements · Geometry · Trigonometry
Internet Archive · Public Domain Mark 1.0. Free to use for anything.
