/*
strike( cannon x,y,speed, target x,y,speed,angle ) = best cannon angle
*/
var cx,cy,cs,ca,px,py,ps,pa;
cx=argument0;
cy=argument1;
cs=argument2;
px=argument3;
py=argument4;
ps=argument5;
pa=argument6;

var dir,alpha,phi,beta;
dir=point_direction(cx,cy,px,py);
alpha=ps/cs;//for every 1 that the bullet moves, the target moves by alpha
phi=degtorad(pa-dir); //pa-dir = distance in radians that pa is above dir
beta=alpha*sin(phi); //
if (abs(beta)>=1)return(-1);
dir+=radtodeg(arcsin(beta));
return dir;