And to make it even faster

I knew it's wrong because I had made the same mistake in my previous research.

It's bigger, simply because it uses some smaller distance to calculate the radians.

The correct one is:

<math>\theta = \int_0^t \frac{v_{lateral}}{d_{initial} + v_{retreat} t}dt</math>

Note that <math>d_{initial} + v_{retreat} t</math> is bigger than (his) <math>(v_{bullet} - v_{retreat})t</math> almost all of the time. Therefore his integral is bigger.