added circumscribe method

src/lab1/graphics/Ellipse.java

 package lab1.graphics;
 
-import java.util.Arrays;
 import java.util.ArrayList;
 
 public class Ellipse extends Shape{
@@ -47,4 +46,9 @@ public class Ellipse extends Shape{
         params=start_s+"\n"+axis_s+"\n"+center_s+"\n"+end_s;
         return params;
     }
+
+    @Override
+    public Ellipse circumscribe() {
+        return new Ellipse(points.get(0), Math.max(a, b), Math.max(a, b));
+    }
 }