DotProduct.as

private function calculateAngle( xPos:Number, yPos:Number ):Number
{
	var pA:Point = new Point( 240, 180 );
	var pB:Point = new Point( xPos, yPos );

	var AP:Point = new Point( 0, 10 );
	var BP:Point = new Point( ( pA.x - pB.x ), ( pA.y - pB.y ) );

	var D:Number = ( AP.x * BP.x ) + ( AP.y * BP.y );

	var A:Number = Math.sqrt( Math.pow( AP.x, 2 ) + Math.pow( AP.y, 2 ) );
	var B:Number = Math.sqrt( Math.pow( BP.x, 2 ) + Math.pow( BP.y, 2 ) );

	var angle:Number = Math.acos( D / ( A * B ) ) * 180 / Math.PI;

	if ( BP.x > 0 )
	{
		angle *= -1;
	}
	
	return angle;
}