A projectile of mass 0.664 kg is shot from a cannon, at height 6.9 m, as shown in the figure, with an initial velocity vi having a horizontal component of 5.7 m/s. The projectile rises to a maximum height of ?y above the end of the cannon's barrel and strikes the ground a horizontal distance ?x past the end of the cannon's barrel. Find the range ?x of the projectile. Answer in units of m.