Electrostatics

Three equal charges are placed on the three corners of a square as shown below. If the magnitude of force between ' $\mathrm{q}_1$ ' and ' $\mathrm{q}_2$ ' is ' $\mathrm{F}_{12}$ ' and that between ' $\mathrm{q}_1$ ' and ' $\mathrm{q}_3$ ' is $\mathrm{F}_{13}$, then the ratio of $F_{13}$ to $F_{12}$ is