Two point charge of equal mass m, charge Q is suspended at a common point by two threads of negligible mass and length l. Show that at equilibrium the inclination angle α of each thread to the vertical is given by $Q^{2}=16\pi \epsilon_{0}mgl^{2}\sin^{2}\alpha\tan\alpha$.

If $\alpha$ is very small, show that $\alpha=\sqrt[3]{\frac{Q^{2}}{16\pi \epsilon_{0}mgl^{2}}}$.