The number of degrees rotation I use is taken directly from the images of WTC7. It is applicable only to WTC7 since it proves the tower fell as a single unit in a vertical or near vertical direction.
The angle of rotation in a natural high rise collapse depends on the point at which the rotation is stopped. If it is the ground that stops it then it will be 90 degrees. If it's another structure close by then it may be 10 degrees or 30 degrees. WTC7 started to fall at an angle within a degree or two of vertical and never more than a few degrees until the chaos of the rubble pile acted on the building towards the end of collapse and the walls shifted violently. Such a movement is only possible with human intervention, i.e. CD.