Lectures on fundamental concepts of algebra and geometry (1911)
Young, John Wesley, 1879-1932, Denton, William Wells, Mitchell, Ulysses Grant · New York : Macmillan · leaf 193
er an analogous situation inspace. Suppose we have two tetrahedra ABCD andABCU (Fig. 22), which are symmetric, that is, mirrorimages of each other. We refuse to call them congruent 180 CONCEPTS OF ALGEBRA AND GEOMETRY for the simple reason that no motion in three-dimensionalspace is possible which… … from the assumptions characterizing such a space thatthere exists a motion which will carry one of thesetetrahedra into the other. From this point of view, thereis no more reason to regard two such tetrahedra as non-congruent than there is to regard the two triangles men-tioned above as…
Algebra · Geometry
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