How to rotate a cylinder on the mouse position ?


I’m trying to rotate a cylinder but I have some issues.
I want that my cylinder rotate in the direction of my mouse position .

I tried some math algorythm like this :

Vector2 _point;
_point = new Vector2(transform.position.x, \ 
this.renderer.bounds.size.y/2 + transform.position.y);
Vector3 mousePos = Input.mousePosition;
mousePos = Camera.main.ScreenToWorldPoint(mousePos);

Vector2 AB = new Vector2(_point.x - transform.position.x, _point.y - \

Vector2 AC = new Vector2(mousePos.x - transform.position.x, mousePos.y - \

Vector2 BC = new Vector2(mousePos.x - _point.x, mousePos.y - _point.y);
float dAB =  Mathf.Sqrt(Mathf.Pow(AB.x,2) + Mathf.Pow(AB.y,2));
float dAC =  Mathf.Sqrt(Mathf.Pow(AC.x, 2) + Mathf.Pow(AC.y,2));
float dBC =  Mathf.Sqrt(Mathf.Pow(BC.x, 2) + Mathf.Pow(BC.y,2));
float toCos = ((AB.x * AC.x) + (AB.y * AC.y))/(dAB *dAC);
float _angle = Mathf.Acos(toCos) * Mathf.Rad2Deg;

_point = new Vector2(mousePos.x, mousePos.y);

It seems to work with the first click but not after.
Is there something wrong with my math algorythm ? Or it with my use of unity object ?

You could just store the Vector3 the mouse is pointing at (by using RayCast) and then use Transform.LookAt.