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 39
figure are to-gether equal to four right angles. Because every interiorangle ABC, with its adja-cent exterior ABD, is e-qual (l3. I.) to two rightangles; therefore all theinterior, together with allthe exterior angles of thefigure, are equal to twiceas many right angles asthere are sides of the fi-…
Euclid's Elements · Geometry · Trigonometry
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