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 297
Cor. If aline turn about a point from the position AB till it comeinto the position AB again, it describes angles which are togetherequal to four right angles. This is evident from the second Cor. tothe 15th. PROP. I. All the exterior angles of any rectilineal figure are together equalto four right… … Let <he line CD, placed id the direction of BC produeeil, turnabout the point C till it coinci»le with CE, a part of the tide C A, andhave described the exterior angle DCE or DC A. Let it then be cgir-ried along the line CA, till itbe in the position AF, that isin the direction of CA produc-ed,…
Euclid's Elements · Geometry · Trigonometry
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