Moment couple (opposite direction on same line)

[yecko]

1. Homework Statement
It is a part of the question in my homework and I extract this out just for the part i m confused(in the picture above)

Homework Equations

Moment couple=d*F
[d is the difference in point of application (=sqrt41) or the perpendicular distance of the forces(=0) ?]

The Attempt at a Solution

As the forces on the same straight line in oppsite direction, I think they will cancel out each other...
Yet, I am not sure if there would be moment formed by the couple...

Thanks

 

[Orodruin]

As the forces on the same straight line in oppsite direction, I think they will cancel out each other...

This is good intuition, but if you are unsure you should back it up with mathematics.

 

[yecko]

This is my mathematical prove

 

[haruspex]

This is my mathematical proveView attachment 212436

Right.