The first six books of the elements of Euclid : with a commentary and geometrical exercises ; to which are annexed a treatise on solid geometry, and short essays on ancient geometrical analysis, and the theory of transversals (1861)
Lardner, Dionysius, 1793-1859 · London : Print. for Taylor and Walton · leaf 285
c. Draw the plane BCa. This cdivides the solid into the pyramid A B C a, and \the solid a b c B C. Draw the plane a b C.This divides the latter solid into two pyramids,whose bases are b c C and B C &, and of which ais the common vertex. The pyramid whosebase is B C b and vertex a is equal to… … BOOK THE SECOND. 267 the vertex a. Hence, in like manner, the pyramid Ca c b is equalto C b c A, for they have the same base C b c and equal altitudes,since A a is parallel to that base. But the pyramid AbcC isequal to the pyramid ABcC, for they have the same base A cCand equal altitudes, since…
Geometry
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