Question

a machine gun is mounted on the top of a tower 100 m high. at what angle should the gun be inclined to cover a maximum range of firing on the ground below? the muzzle speed of bullet is 150 m/s. take g=10m/s.

Answer 1

let r be range.
\[r=\max \Rightarrow \frac{ dr }{ d\theta}=0\]
solve for $$\theta$$

Answer 2

shouldn't it be 45 degrees? :O.. what am i missing?