When calculating theta in the last step, I believe arcsin should be used instead of arctan, since the length of the beam does not change (the hypotenuse), but the length of 6m gets smaller as the beam tilts (due to the roller at B)
@@adamfadley4224 Support B is a roller, so it's able to move. If we assume what the video did, then we are implying that the beam somehow got longer. B can move freely in the x direction
