Projectile movement in 3D

I am trying to simulate a projectile artillery shot, I am using the projectile formulas to simulate this movement, but the problem is, I am not finding a way to transform this into 3D coordinates, I can get only the x and y.

What I want to do is transform the (x,y) coordinates I am calculating alongside the initial forward Vector of the gameobject associated with the following script:

 #pragma strict
 
 public class ArtilleryShot extends MonoBehaviour{
     
     var startTime:float ;
     var target:Transform;
     private var destination:Vector3;
     private var distanceToDestination:float;
     private var velocity:float = 20.0;
     private var vx:float;
     private var vy:float;
     private var g:float = 10.0;
     private var x0:float;
     private var y0:float;
     var launchExplosion:GameObject;
     var explosion:GameObject;
     var damage:float;
     var launchPoint:GameObject;
     
     function Start(){
         var explosion:GameObject = GameObject.Instantiate(launchExplosion,transform.position,transform.rotation);
         explosion.transform.localScale = Vector3(4,4,4);
         
         startTime = Time.time;
         destination = target.position;
         distanceToDestination = Vector3.Distance(transform.position, destination);
         //velocity = Mathf.Sqrt((distanceToDestination*g)/(Mathf.Sin(Mathf.Deg2Rad*120)));
         velocity = Mathf.Sqrt((distanceToDestination*distanceToDestination*g)/(2*Mathf.Cos(Mathf.Deg2Rad*60)*Mathf.Cos(Mathf.Deg2Rad*60)*(transform.position.y+(distanceToDestination*Mathf.Tan(Mathf.Deg2Rad*60)))));
         vx = velocity * Mathf.Cos(Mathf.Deg2Rad*60);
         vy = velocity * Mathf.Sin(Mathf.Deg2Rad*60);        
         x0 = transform.position.x;
         y0 = transform.position.y;
     }
     
     function Update(){
         var t:float = Time.time-startTime;
         
         if(t==0)
           return;
         var newPos = transform.position;
         
         newPos.x = x0+(vx*t);
         var downY:float = (-.5*g*t*t);
         var y:float = vy*t+downY;
         newPos.y = y0+y;
         
         var distance = Vector3.Distance(transform.position,newPos);
         var angle = Vector3.Angle(launchPoint.transform.forward,newPos);
         //newPos should be projected alongside the forward axis before setting the new position
         transform.position = newPos;
         
     }    
     
     function SetTarget(targetParam:Transform){
         target = targetParam.transform;
     }
     
     function OnTriggerEnter(other:Collider){
         if(other.gameObject.tag=="EnemyGroundUnit" || other.gameObject.tag=="Ground"){
             var explosionGameObject = GameObject.Instantiate(explosion,transform.position,transform.rotation);
             explosionGameObject.transform.localScale = Vector3(4,4,4);
             other.gameObject.SendMessage("TakeDamage",damage);
             Destroy(gameObject);
         }
     }
     
     function SetPointOfOrigin(launchPointParam:GameObject){
         launchPoint = launchPointParam;
     }
 }