A treatise on special or elementary geometry (1877)
Olney, Edward, 1827-1887, Olney, Edward, 1827-1887. Elements of trigonometry, plane and spherical · New York : Sheldon · leaf 223
Since AB and db are intersections of two parallelplanes by a third plane, they are parallel (?). Soalso he is parallel to BC, cd to CD, etc. Hence,angle 6 = B, c = C, etc. (?), and the polygons aremutually equiangular. Again, aJ : AB :: S6 : SB,and 5c : BC :: S5 : SB (?). Hence, ab : be :: AB■ BC… … PROPOSITION n. Sll* Tlieorem,—IfUuo pyramids of the same altitude are cuthy planes equally distant from and parallel to their bases, the sections are to each other as the bases. Dem.—Let S-ABC and S-ABCDE betwo pyramids of the same altitude, cut bythe planes abc and abcde, parallel to andat equal…
Geometry · Trigonometry
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