I'm not a huge fan of the way ball trajectories are often done because they take it from where the ball landed. Imagine a half circle, the right side being where the hitter hit the ball, and the left side being where it would land (it's not exactly that shape, but it's roughly accurate for this). What they'll do is they'll take the point it hit a seat for example, which is a point on that half circle towards the end (on the left), but not all the way. Then draw a line straight down, and a line right back to the original point. The distance of the ball was not accurately measured.