Given the image below, is it possible to calculate the angles E and/or F given the angles $A,B,C$ and $D$?
The situation is as follows:
Two observers each measure the angle between point $1$ and point $2$ (these angles are $A$ and $C$ respectively) and point $2$ and point $3$ ($B$ and $D$).
The three points are the same real-world points for both observers, but the exact location (distance etc) of both points is unknown.
Is it possible to calculate the angle $E$ and/or $F$ here? It feels like this should be possible but I'm not entirely sure if and how. The reason I think this is that given the two measured angles, there's only one possible position for the observer to be (if the points were in a straight line, there could be another point on the other side of the line but let's disregard that for now). Given that we have the two observer points for which we know that there is only one possible location, it feels like it should be possible to then calculate the angle between the two of them.
The angles $A$,$B$,$C$ and $D$ doesn't determine the angles $E$ or $F$