My circuit looks similar to this:

When I calculate \[V_{TH}\] in this circuit, there is no current flowing through \[R_2\] so it is taken out of the equation. However when I calculate \[R_{TH}\] , I am supposed to use it in the equation.

I don't understand this. If there is no voltage drop across \[R_2\] and no current flowing through it, why is its existence even taken into account when calculating total resistance?

Thanks,

Winger