Reading 1N.4.6, it seems my definitions are incorrect, because "R_out_A is much smaller than R_in_B" (regarding a voltage divider B chained to a voltage divider A) makes no sense because R_out_A and R_in_B are one and the same according to my definition. I'm (oxymoronically) clearly not understanding something.
In section "1N.4.6 - A rule of thumb for relating R_out_a to R_in_b" of "Learning the Art of Electronics", it starts talking about R_in and R_out. R_in was mentioned, and I think it's the internal resistance (=R_thevenin?). However, what is R_out? Also, if I misunderstood R_in, correct me on that, too.
I have a Q that I don't believe it's worthy of a SE post, because it's specific to a book (LAoE). Is this a good place to ask a question? If not, where should I?
@Xam -- Well, I frankly don't know. I'm not planning to pursue a math degree, so I'm probably not into math as others. However, I do like geometry (I'm currently trying to solve a puzzle given to me by a mathematician). But I really can't wait until I learn Taylor series.