The first six books of the elements of Euclid : with a commentary and geometrical exercises ; to which are annexed a treatise on solid geometry, and short essays on ancient geometrical analysis, and the theory of transversals (1861)
Lardner, Dionysius, 1793-1859 · London : Print. for Taylor and Walton · leaf 291
-spectively, let right lines equalto the side of the pentagon beinflected on this perpendicu-lar. Since the side of a re- pgular pentagon is greater than the radius of its circumscribingcircle, these lines will meet the perpendicular below the planeof the pentagon; and since the lines so inflected… … BOOK THE THIRD. 2JS which is two thirds of a right angle. Two of the plane angleswhich form each solid angle at the base of the pyramid have evi-dently the same inclination as any two of the plane angles whichform the solid angle P, being, in fact, the same planes. Hencethe solid angles A, B, C,…
Geometry
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