What is the potential energy of this group of electron charges?

[yo_man]

Homework Statement

Three electrons form an equilateral triangle 1.10 nm on each side. A proton is at the center of the triangle.
What is the potential energy of this group of charges?

Homework Equations

potential energy = U = kq1q2/r

The Attempt at a Solution

So, I was assuming that the three electrons, since they form an equilateral triangle, their charges will cancel out and I should just find the potential energy based on the positive charge.

so then I substituted q1 for the proton, but then since there is a q2, i also tried to use the charge of an electron.

also, I found the radius from the center proton of the triangle to the corner electron of the triangle to be 0.635 m

I'm just not sure what to do anymore I only have a few attempts left

 

[Google_Spider]

I found the radius from the center proton of the triangle to the corner electron of the triangle to be 0.635 m

?? meter ??
I will take it as 0.635 nm.

potential energy of the system=k[\frac{3e^2}{1.10X10^-9}-\frac{3e^2}{0.635X10^-9}]

We can make three electron-electron pairs and three proton-electron pairs.

 

[Rusty Shackle]

?? meter ??
I will take it as 0.635 nm.

potential energy of the system=k[\frac{3e^2}{1.10X10^-9}-\frac{3e^2}{0.635X10^-9}]

We can make three electron-electron pairs and three proton-electron pairs.

So what am I supposed to plug in for e? +1, -1 ??