How does C++ calculate the area of circles, rectangles and triangles

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Topic description

Using polymorphism to write a program, declare the abstract base class Shape, from which three derived classes are derived: Circle (circle), Rectangle (rectangle) and Triangle (triangle). A function printArea () is used to output the area of the above three respectively (the result retains two decimal places). The data of the three graphics are given when defining the object.

Input

The radius of a circle, the side of a rectangle, the base and height of a triangle.

Output

The area of a circle

The area of a rectangle

The area of a triangle

Note: there is a carriage return after each line

Sample input

12.6 4.5 8.4 4.5 8.4

Sample output

Area of circle=498.76

Area of rectangle=37.80

Area of triangle=18.90

Code implementation # include#include # define PI 3.1415926using namespace std;class Shape {public: virtual double printArea () = 0;}; class Circle:public Shape {private: double r; public: Circle (double x) {rystx;} virtual double printArea () {return PI*r*r;}}; class Rectangle:public Shape {private: double wm m h Public: Rectangle (double Xrem double y) {wimpy;} virtual double printArea () {return wigh;}}; class Triangle:public Shape {private: double wrech; public: Triangle (double xrem double y) {wimpy } virtual double printArea () {return wreckhpact 2;}}; double printArea (Shape & x) {return x.printArea ();} int main () {double a > > b > > c > > d > > e; Circle cir (a); Rectangle rec (bMagee c); Triangle tri (dMagne); cout