Q-3(b) (7 marks) Describe abstract class called Shape which has three subclasses say Triangle, Rectangle, Circle. Define one method area() in the abstract class and override this area() in these three subclasses to calculate for specific object i.e. area() of Triangle subclass should calculate area of triangle etc. Same for Rectangle and Circle. abstract class Shape{ abstract void area(); } class Circle extends Shape{ double r; Circle(double r) { this.r=r; } void area() { double a=(3.14*r*r); System.out.println("Area of circle having radius "+r+" is:"+a); } } class Rectangle extends Shape{ double w,h; Rectangle(double w,double h) { this.w=w; this.h=h; } void area() { double a=(h*w); System.out.println("Area of rectangle having width "+w+" and height "+h+" is:"+a); } } class Triangle extends Shape{ double b,h; Triangle(double b,double h) { this.b=b; this.h=h; } void area() { double...