Help me in solving LCPPCL30 problem

My issue

                                                                                                                                                                        are a of circle using double data type 

My code

#include <iostream>
using namespace std;

int main() {
    
double area ;
    double pi = 3.14;
    
    double radius=8.9;
    cout << radius ;
    cout<<    pi                        ;                                                                                   
    
    area=pi*radius*radius;
    cout<<area;
    
    // declare radius and area as double
    
    
    cout << "The Area of the given Circle is " << area << endl;

}

Learning course: ATT - C++
Problem Link: Double datatype Practice Problem in ATT - C++ - CodeChef