Vector Addition? (AS3 Physics)

programming flash
1

Hey guys I have a simple (I hope) problem for AS3.

Say for example I have a ball and I would like to move it towards a specific angle and a specific magnitude I would use something like:

var myMag:int = 2
var myAngle:int = 10

var speedx:int =Math.sin(myAngle*(Math.PI/180))*2*myMag;
var speedy:int = Math.cos((myAngle*(Math.PI/180))*2*-1)*myMag;


x+=speedx*speed;
y+=speedy*speed;

Now if I wanted to change this force, for example, add a force to it, say, with magnitude 0.5 and angle 20, how would I do that?
Thanks!