Just watch Implement of trigonometry to real life circumstances and machines. Shooting angle is what the direction should the gun point to when standing at the main radar (the middle one, (0;0)) Distance is the distance from the main radar to the aircraft.
Circle drawing algorithm in this link, written by @thoble_779 https://scratch.mit.edu/discuss/topic/294560/?page=1#post-4226404 This demonstrates how radar coordinate aircrafts and communicate when the aircrafts are flying
