physics problem
 

In Figure 13-34, a square of edge length 19.0 cm is formed by four spheres of masses m1= 6.00g, m2= 4.00 g, m3= 1.00 g, and m4= 6.00 g. In unit-vector notation, what is the net gravitational force from them on a central sphere with mass m5= 2.50 g?

All of the masses are the same distance from m5, and the distance is d= 13.44 cm 0.1344 m.

How exactly can come up with whats in the bold? This is an example of a problem I have to do, and I know how to work it, I just can't figure out how they found this distance. Is there a certain equation for this?

Thanks in advance

scratch that, I didn't see that you knew how to solve it.

So you don't need to know how to solve it? I would have just assumed that they made the distance up. It's just a homework problem.

They get the distance by drawing a line from m5 to each of the masses.
The length of the side of the square is 19, so the length of the diagonal is 19*sqrt(2), so half the diagonal is 9.5*sqrt(2) = 13.44

thank you!
kutulu - the problem I had had different masses and length and I was given the way to work it out, I just couldnt figure out how they found the distance, so I couldn't do the rest of the work past the distance

I just added in part of the answer..