How Are These Resistors in Parallel

[FAS1998]

I’ve included an image of a solution to a problem from my textbook. Part of the problem is to find the equivalent resistance of the given circuit. In the solution they seem to be treating the resistors as if they were in parallel. I don’t understand why they are doing this.

For the two resistors to be in parallel would they not need to have both nodes in common? The resistors in the series don’t appear to have this property.

[Moderator's note: Moved from a technical forum and thus no template.]

 

[haruspex]

I’ve included an image of a solution to a problem from my textbook. Part of the problem is to find the equivalent resistance of the given circuit. In the solution they seem to be treating the resistors as if they were in parallel. I don’t understand why they are doing this.

For the two resistors to be in parallel would they not need to have both nodes in common? The resistors in the series don’t appear to have this property.

[Moderator's note: Moved from a technical forum and thus no template.]

It might clarify matters if you post the whole question.

 

[FAS1998]

It might clarify matters if you post the whole question.

Here’s the original question. It states that the circuit is a voltage divider, which I believe implies that the resistors are in series, and then the solution uses the equation for resistors in parallel to calculate the equivalent resistance.

I’ve seen similar things elsewhere in the textbook solutions so I assume I’m doing something wrong, and it’s not just a mistake in the solution.

 

[haruspex]

Here’s the original question. It states that the circuit is a voltage divider, which I believe implies that the resistors are in series, and then the solution uses the equation for resistors in parallel to calculate the equivalent resistance.

I’ve seen similar things elsewhere in the textbook solutions so I assume I’m doing something wrong, and it’s not just a mistake in the solution.

The key is the meaning of "equivalent output resistance".
See if the answer given here helps:
https://electronics.stackexchange.com/questions/265800/voltage-divider-output-resistance?rq=1