finding rotations between 2 points in COMSOL

So I have the results of an eigenfrequency analysis, and would like to find out how much an object has rotated in a certain plane. For instance, in the picture below, I'd like to find out how much the front surface of the "red" block there has rotated in the y-z plane. I extracted the displacement data of the upper corners of the block, and used their initial positions to calculate the final position of each corner, and then use arc tan to find the angle. But I'm getting 45 degrees instead of approximately 0, as what the picture below indicates. What's wrong with my approach, or maybe anyone knows how to extract rotation of a certain plane directly from COMSOL? ​ ​ https://i.redd.it/jercerx1o7031.png submitted by /u/aldosebastian [link] [comments]

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