java question...

I also posted question 3

Every circle has a center and a radius. Given the radius, we can determine the circles area and circumference. Given the center, we can determine its position in the x-y plane. The center of a circle is a point in the x-y plane. Design the class Circle that can store the radius and center of the circle. Because the center is a point in the x-y plane and you designed the class to capture the properties of a point in Programming Exercise 3, you must derive the class Circle from the class Point. You should be able to perform the usual operations on a circle, such as setting the radius, printing the radius, calculating and printing the area and circumference, and carrying out the usual operations on the center.

3. Suppose that a class Employee is derived from the class Person (see Example 8-8, in Chapter 8). Give examples of data and method members that can be added to the class Employee.