Resistance between two points in complex circuit

[Anonimas]

Homework Statement

I have attached a circuit scheme from old textbook. Basically, there are 17 resistors which every has resistance R and we need to find the resistance between points A and B. (I added numbers to each resistor so it would be easier to communicate).
Extra question of mine - is the equivalent resistance equal to that between points A and B?

Homework Equations

R = R1 + R2 + R3 + ...
1 / R = 1 / R1 + 1 / R2 + 1 / R3 +...

The Attempt at a Solution

I have solved some resistors circuits exercises, but this one is more complex. I simply added 1st resistor with 3rd and 2nd with 5th, because they are in series. Now I am stuck, because I am not sure which resistors are in parallel and which are not, because they are combining to each other. I would be grateful if someone would explain from where should I start or show an example of how to solve such type of circuits.

 

[SammyS]

Homework Statement

I have attached a circuit scheme from old textbook. Basically, there are 17 resistors which every has resistance R and we need to find the resistance between points A and B. (I added numbers to each resistor so it would be easier to communicate).
Extra question of mine - is the equivalent resistance equal to that between points A and B?

Homework Equations

R = R1 + R2 + R3 + ...
1 / R = 1 / R1 + 1 / R2 + 1 / R3 +...

The Attempt at a Solution

I have solved some resistors circuits exercises, but this one is more complex. I simply added 1st resistor with 3rd and 2nd with 5th, because they are in series. Now I am stuck, because I am not sure which resistors are in parallel and which are not, because they are combining to each other. I would be grateful if someone would explain from where should I start or show an example of how to solve such type of circuits.

Hello Anonimas. Welcome to PF !

Use symmetry.

If a voltage applied across A & B, then all of the following nodes will be at a voltage half way between the voltages at A and at B.

the node joining R₁, R₂, and R₄

the node joining R₄, R₆, R₇, and R₉

the node joining R₉, R₁₁, R₁₂, and R₁₄

the node joining R₁₄, R₁₆, and R₁₇
​

If there is no potential difference between any of those, then what what does that say about the current R₄, R₉, and R₁₄

 

[Anonimas]

Thank you for information,
I'll try to find out :)