random spawn around a circle

Assets/Scripts/SpawnAsteroids.cs

@@ -4,10 +4,16 @@ using System.Collections;
 public class SpawnAsteroids : MonoBehaviour {
 
     public GameObject myAsteroid;
-    public Vector3 initialPosition;
+    Vector3 center;
+    float x;
+    float y;
+    float d;
 
 	// Use this for initialization
-	void Start () {
+    void Start()
+    {
+        center = new Vector3(0, 0);
+        d = 4;
         InvokeRepeating("Spawn", 0, 0.5F);
 	
 	}
@@ -20,6 +26,16 @@ public class SpawnAsteroids : MonoBehaviour {
     void Spawn()
     {
         GameObject instance = Instantiate(myAsteroid);
-        instance.transform.position = new Vector3(10, 10, 0);
+        instance.transform.position = getPositions();
     }
+
+    Vector3 getPositions()
+    {
+        float theta = Random.Range(0F, 360F);
+        x = center.x - Mathf.Sin(theta) * d;
+        y = center.y - Mathf.Cos(theta) * d;
+        return new Vector3(x, y);
+    }
+
+
 }