Move the line renderer in a circle with only left and right arrow keys

I am trying to move the line renderer (as an aim) in a circle with only left and right arrow keys but I have difficulties with it. Here is the image of how my game looks.

and here is my script (not completed)

public class aiming: MonoBehaviour
{
    LineRenderer lr;
    float input;


    void Start()
    {
        lr = GetComponent<LineRenderer>();

    }

    private void FixedUpdate()
    {

      // move the line renderer at index 1 depending on the input value

    }

    void Update()
    {

        input = Input.GetAxisRaw("Horizontal");
        
    }
}

Concept

  1. Make parent object for Line and reset transform of that parent object.
    [195220-image.png|195220]
  1. Rotate Line parent on desired axis. In this example on Z.
    [195221-image-1.png|195221]
  1. Control this axis with script. A key increase D key decrease. Don’t forget to clamp those values.