kaoriz

Hi, I recently started physics and I am so lost! I need to calculate the exact act of a cannon firing a projectile at series of targets a known distance away. Here's what I know: muzzle velocity of cannon: 31 meters/second cannon length: 1.143 meters The targets are, 50 m, 75 m, and 100 m, away. What equation(s) do I use to calculate the launch angles? Any help is greatly appreciated! =D