Recall, the path of the projectile was given as by the following parametric equations:

     x = (Ucosθ)t
     y = (Usinθ)t - 0.5gt²

For U = 400 ft/s and θ = 60^o, the parametric equations reduce to:

     x = (400 cos 60)t = 200t
     y = (400 sin 60)t - 0.5(32.2)t² = 346.4t - 16.1t²

When the projectile hits the ground, y is zero. Thus,

     346.4t - 16.1t² = 0
     16.1t² = 346.4t
     t = 346.4/16.1 = 21.52 s

The corresponding x-position of the projectile is

     x = 200(21.52) = 4,304 ft

Based on the parametric equations, the positions of the trajectory are determined by varying the time t. The trajectory of the projectile is plotted in the figure shown on the left.