How do you find the period of a binary star system? (exact question is "A binary star system consists of two stars of masses m1 and m2 orbiting about each other. Suppose that the orbits of the stars are circles of radii r1 and r2 centered on the center of mass. The center of mass is a point between the stars such that the radii r1 and r2 are in the ratio r1/r2 = m2/m1. Show that the period of the orbital motion is given by T^2 = 4π^2/(G(m1+m2))((r1+r2)^3)).