Vector2.SignedAngle

Parameters

Returns

float The signed angle in degrees between the two vectors.

Description

Gets the signed angle in degrees between from and to.

The angle returned is the signed counterclockwise angle between the two vectors.
Note: The angle returned will always be between -180 and 180 degrees, because the method returns the smallest angle between the vectors. That is, it will never return a reflex angle. Angles are calculated from world origin point (0,0,0) as the vertex.
Additional resources: Angle function.

using UnityEngine;

public class Vector : MonoBehaviour
{
    //Use these to get the GameObject's positions
    Vector2 m_MyFirstVector;
    Vector2 m_MySecondVector;

    float m_Angle;

    //You must assign to these two GameObjects in the Inspector
    public GameObject m_MyObject;
    public GameObject m_MyOtherObject;

    void Start()
    {
        //Initialise the Vector
        m_MyFirstVector = Vector2.zero;
        m_MySecondVector = Vector2.zero;
        m_Angle = 0.0f;
    }

    void Update()
    {
        //Fetch the first GameObject's position
        m_MyFirstVector = new Vector2(m_MyObject.transform.position.x, m_MyObject.transform.position.y);
        //Fetch the second GameObject's position
        m_MySecondVector = new Vector2(m_MyOtherObject.transform.position.x, m_MyOtherObject.transform.position.y);
        //Find the angle for the two Vectors
        m_Angle = Vector2.SignedAngle(m_MyFirstVector, m_MySecondVector);

        //Draw lines from origin point to Vectors
        Debug.DrawLine(Vector2.zero, m_MyFirstVector, Color.magenta);
        Debug.DrawLine(Vector2.zero, m_MySecondVector, Color.blue);

        //Log values of Vectors and angle in Console
        Debug.Log("MyFirstVector: " + m_MyFirstVector);
        Debug.Log("MySecondVector: " + m_MySecondVector);
        Debug.Log("Angle Between Objects: " + m_Angle);
    }

    void OnGUI()
    {
        //Output the angle found above
        GUI.Label(new Rect(25, 25, 200, 40), "Angle Between Objects" + m_Angle);
    }
}