I am a student. Our teacher gave us a problem that can be done by Kirchhoff's laws. The problem is that in the second case we have to calculate β → ∞, the teachers told us to calculate β using a limit, but I don't know how to do this if there is no function to take the limit to ∞. This is the only information the problem gives. The (O1) and (O2) squares are loops from second Kirchhoff's law.