4. Write a program that computes the area of a circular region (the shaded area in the diagram) given the radii of the inner and the outer circles, rị and r, respectively. We compute the area of the...

Extracted text: 4. Write a program that computes the area of a circular region (the shaded area in the diagram) given the radii of the inner and the outer circles, rị and r, respectively. We compute the area of the circular region by subtracting the area of the inner circle from the area of the outer circle. Define a Circle class that has methods to compute the area and circumference. You set the circle's radius with the setRadius method or via a constructor.