I wasn't sure what category to put this in, but here's my problem.(adsbygoogle = window.adsbygoogle || []).push({});

There is a parallelogram with 3 given points for its corners (each with 3 different coordinates). The idea is to find the forth point. I've tried subbing (x,y,z) for the unknown point, and creating 4 vectors. I tried equating the cross product of two opposite vectors to zero as well as absolute value of opposite vectors to each other. This left me with alot of algebra after I combined both methods and then cheated to get a decimal answer which I'm not even sure is correct. Is there an easier way to do this problem that I'm missing? Thanks.

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# Parallelogram in 3D space

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