My Technic math puzzle of the day

[N. W. Perry]

I think the key is in the ced triangle.

If you adjust it so e is parrallel to d distance to the shock center wise.

Like so:


Then find the distance of E' to D, which leads to the angle at A

Not tested though.

Trouble is, I don’t know the exact position of D relative to E’, only to AB or (local) y of B. A complication, of course, is that the shock is adjustable, so that length is not consistent.