@article {MATHEDUC.06322209,
author = {Bergold, Helmut},
title = {A generalization of Pohlke's theorem. (Eine Verallgemeinerung des Satzes von Pohlke.)},
year = {2014},
journal = {Elemente der Mathematik},
volume = {69},
number = {2},
issn = {0013-6018},
pages = {57-60},
publisher = {European Mathematical Society (EMS) Publishing House, Zurich},
doi = {10.4171/EM/247},
abstract = {This generalised theorem states: Any two parallelepipeds in 3-space can be rotated in such a way that they ``look identical'', meaning that their projections onto a plane perpendicular to the direction of view are congruent. For the proof, one can assume that the orthogonal projection $O$ is along the 3-axis onto the 1-2-plane. The vectors spanning the edges of the two parallelepipeds are written as the columns of the two matrices $V_1$ and $V_2$, respectively. The statement of the theorem then translates into $OW_1 V_1=OW_2 V_2$ for suitable conformal-orthogonal transformation matrices $W_1,W_2$. The author then proves that for any 3-by-3-matrix $M$ of rank $\geq 2$, there exist suitable $W_1,W_2$ such that $OW_1M=OW_2$. In particular, this holds for $M=V_1 V_2^{-1}$, which proves the theorem.},
reviewer = {Wolfgang Globke (Adelaide)},
msc2010 = {G40xx (H60xx)},
identifier = {2015e.00608},
}