Given two congruent triangles
![A_1A_2A_3](/media/m/b/b/c/bbcede562021e40de971618cb504b791.png)
and
![B_1B_2B_3](/media/m/0/9/7/097c78d111b6366ea01e13f3316f0d00.png)
(
![A_iA_k = B_iB_k](/media/m/3/3/b/33b4a3fbfe3e22f263e0b75b289843a5.png)
), prove that there exists a plane such that the orthogonal projections of these triangles onto it are congruent and equally oriented.
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Given two congruent triangles $A_1A_2A_3$ and $B_1B_2B_3$ ($A_iA_k = B_iB_k$), prove that there exists a plane such that the orthogonal projections of these triangles onto it are congruent and equally oriented.