Well, I don't know how to explain it, but I know how to use it

I used it in my fireball script for example;
PHP Code:
function onCreated() {
showCharacter();
setCharAni( this.info[ 0], "");
this.r_target = findPlayer( this.info[ 1]);
this.r_moves = 0;
moveIt();
}
function onMovementFinished() {
if ( this.r_moves = 20)
destroy();
if ( this.x in | this.r_target.x - 2.5, this.r_target.x + 2.5| && this.y in | this.r_target.y - 2.5, this.r_target.y + 2.5|) {
triggerAction( this.r_target.x + 0.5, this.r_target.y + 0.5, "projectile", this.info[ 2]);
destroy();
}
else
moveIt();
}
function moveIt(){
this.r_angle = getangle( this.r_target.x - this.x, this.r_target.y - this.y);
move( cos( this.r_angle) * 5.5, - sin( this.r_angle) * 5.5, .4, 8);
this.r_moves ++;
}
It has to do with angles and stuff.. like
sinus and
tan also do.