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 38
ngles of every triangle are equal totwo right angles. Let ABC he a triangle, and let one of its sides BC be produced toD ; the exterior nns\e ACD is equal to the two interior and oppositeangles CAB, ABC ; and tl.e three interior angles of the triangle, viz*ABC, BCA, CAB, are together equal to two… … 38 JELKMENTS parallel to CE, and BD falls upon them, tbp exterior angle ECl) isequal to the interior and opposite ansle ABC : liut (he ani^le ACEwas shown to be equal to the angle BAC ; therelore the whole exteri-or angle ACD is equal to the two interior and oj»posi!e angles CAB,ABC ; to the«e…
Euclid's Elements · Geometry · Trigonometry
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