Consider three latex particles interacting through a screened Coulomb pair potential U =…

Consider three latex particles interacting through a screened Coulomb pair potential U = [exp(-rij/hd)]/rc, where rc is the distance between particles i and j. Fix two of the particles, and let the third move on a locus at any fixed distance measured from the midpoint of the first two. Show that the sum of the pair potentials is a minimum when the centres of the three particles form an isosceles triangle, and is a maximum when the particles are colinear.