The elements of Euclid : viz, the first six books, together with the eleventh and twelfth : the errors, by which Theon, or others, have long ago vitiated these books, are corrected, and some of Euclid's demonstrations are restored : also, The book of Euclid's data, in like manner corrected (1834)
Euclid, Euclid, Simson, Robert, 1687-1768 · Philadelphia : Desilver & Thomas · leaf 202
endicular to the Cplane CD, and the straight line EG,which is in that plane, meets it;therefore FGE is a right angle (3.def. 11.): but EF is also at right an-gles to the plane AB; and thereforeEFG is a right angle: whereforetwo of the angles of the triangleEFG are equal together to two rightangles;… … B PROP. XXXIX. THEOR. In a solid parallelepiped, if the sides of two of theopposite planes be divided each into two equal parts,the common section of the planes passing through thepoints of division, and the diameter of the solid paral-lelopiped cut each other into two equal parts.* See Note, 200…
Mathematics, Greek · Geometry · Trigonometry
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