Simple 2d reflection question

[source="c#"]var lineMag:Number = Math.sqrt(vLine.x * vLine.x + vLine.y * vLine.y);					var v1v:Point = new Point(particles.vel.x, particles.vel.y);var v2v:Point = new Point(vLine.x, vLine.y);var v2n:Point = new Point(v2v.y, -v2v.x);//normal					var proj1:Point = new Point();var proj2:Point = new Point();					var dp1:Number = v1v.x * v2v.x + v1v.y * v2v.y;					proj1.x = ( dp1 / (v2v.x * v2v.x + v2v.y * v2v.y) ) * v2v.x;proj1.y = ( dp1 / (v2v.x * v2v.x + v2v.y * v2v.y) ) * v2v.y;					var dp2:Number = v1v.x * v2n.x + v1v.y * v2n.y;		proj2.x = -( dp2 / (v2n.x * v2n.x + v2n.y * v2n.y) ) * v2n.x;proj2.y = -( dp2 / (v2n.x * v2n.x + v2n.y * v2n.y) ) * v2n.y;			var friction:Number = 1;var bounce:Number = 1;				particles.vel.x = proj1.x * friction + proj2.x * bounce;particles.vel.y = proj1.y * friction + proj2.y * bounce;

[source = "c#"]Vector2 vLine = p2 - p1;//above line just does this://vLine.x = p2.x - p1.x;//vLine.y = p2.y - p1.y;float lineMag = (float)Math.sqrt(vLine.x * vLine.x + vLine.y * vLine.y);					Vector2 v1v = new Vector2(particle.vel.x, particle.vel.y);Vector2 v2v = new Vector2(vLine.x, vLine.y);Vector2 v2n = new Vector2(v2v.y, -v2v.x);//normal					Vector2 proj1 = new Vector2();Vector2 proj2 = new Vector2();					float dp1 = v1v.x * v2v.x + v1v.y * v2v.y;					proj1.x = ( dp1 / (v2v.x * v2v.x + v2v.y * v2v.y) ) * v2v.x;proj1.y = ( dp1 / (v2v.x * v2v.x + v2v.y * v2v.y) ) * v2v.y;					float dp2 = v1v.x * v2n.x + v1v.y * v2n.y;		proj2.x = -( dp2 / (v2n.x * v2n.x + v2n.y * v2n.y) ) * v2n.x;proj2.y = -( dp2 / (v2n.x * v2n.x + v2n.y * v2n.y) ) * v2n.y;			float friction = 1;float bounce = 1;				particle.vel.x = proj1.x * friction + proj2.x * bounce;particle.vel.y = proj1.y * friction + proj2.y * bounce;